Với $a$ và $b$ là các số thực dương tùy ý, $\log a+\log b$ bằng

Read the text carefully and then choose the correct answer (A, B, C or D) for each sentence  

If you are invited to someone’s house in America for dinner, you should bring a gift, such as a bunch of flowers or a box of chocolates. If you give your host a wrapped gift, he/she may open it in front of you. Opening a gift in front of the gift-giver is considered polite. It shows that the host is excited about receiving the gift and wants to show his/her appreciation to you immediately. Even if the host doesn’t like it, he/she will tell “a white lie” and say how much they like the gift to prevent the guest from feeling bad. If your host asks you to arrive at the particular time, you should not arrive exactly on time or earlier than expected time, because this is considered to be inconvenient and therefore rude, as the host may not be ready.  

Question: When invited for dinner, you shouldn’t arrive exactly on time because ______.

Reading the passage carefully and choose the correct answer (A,B,C or D) for each sentence from 28 to 31.

Education (28)_________ another area of social life in which information technology is changing the way we communicate. Today’s college students may not simply sit in a lecture or a library (29)__________ about their field. Through their computers and the wonders of virtual reality, they can participate (30) ______________ lifelike stimulated experiences. Consider the following scenario of the future of (31) ____________ mae possible through developments in information technology.  

Question 28:

Question 20: Which of the following is TRUE according to the passage?   

It is commonly believed that school is where people go to get an education. Nevertheless, it has been said that today children interrupt their education to go to school. The difference between schooling and education implied by this remark is important. Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist. Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is a very broad, inclusive term. It is a lifelong process, a process that starts long before the start of school, and one that should be an integral part of one's entire life. Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at approximately the same time, take assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their communities or what the newest filmmakers are experimenting with. There are definite conditions surrounding the formalized process of schooling.        

Question 21: The word "they" in the last paragraph refers to ____________________  

It is commonly believed that school is where people go to get an education. Nevertheless, it has been said that today children interrupt their education to go to school. The difference between schooling and education implied by this remark is important. Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist. Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is a very broad, inclusive term. It is a lifelong process, a process that starts long before the start of school, and one that should be an integral part of one's entire life. Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at approximately the same time, take assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their communities or what the newest filmmakers are experimenting with. There are definite conditions surrounding the formalized process of schooling.         

Question 24: In the passage, the expression "children interrupt their education to go to school" mostly implies that

It is commonly believed that school is where people go to get an education. Nevertheless, it has been said that today children interrupt their education to go to school. The difference between schooling and education implied by this remark is important. Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist. Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is a very broad, inclusive term. It is a lifelong process, a process that starts long before the start of school, and one that should be an integral part of one's entire life. Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at approximately the same time, take assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their communities or what the newest filmmakers are experimenting with. There are definite conditions surrounding the formalized process of schooling.           

Question 26: Which of the following would the writer support?  

It is commonly believed that school is where people go to get an education. Nevertheless, it has been said that today children interrupt their education to go to school. The difference between schooling and education implied by this remark is important. Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist. Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is a very broad, inclusive term. It is a lifelong process, a process that starts long before the start of school, and one that should be an integral part of one's entire life. Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at approximately the same time, take assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their communities or what the newest filmmakers are experimenting with. There are definite conditions surrounding the formalized process of schooling.         

Question 27: According to the passage, the doers of education are __________________   

It is commonly believed that school is where people go to get an education. Nevertheless, it has been said that today children interrupt their education to go to school. The difference between schooling and education implied by this remark is important. Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist. Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is a very broad, inclusive term. It is a lifelong process, a process that starts long before the start of school, and one that should be an integral part of one's entire life. Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at approximately the same time, take assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their communities or what the newest filmmakers are experimenting with. There are definite conditions surrounding the formalized process of schooling.        

Dùng một lực có độ lớn F nằm ngang kéo quả cầu con lắc cho dây treo lệch khỏi phương thẳng đứng một góc như hình vẽ. Khi trọng lượng của quả cầu là 20 N thì độ lớn lực căng dây là T. Giá trị của T gần giá trị nào nhất sau đây?  

Một chất điểm đứng yên dưới tác dụng của ba lực có độ lớn lần lượt là F1, F2 = 6 N và F3. Nếu góc hợp bởi giữa hai lực F1 và F3 là 600 thì F3 có thể bằng  

Một vật rắn chịu tác dụng của hai lực  và  , để vật ở trạng thái cân bàng thì