Hòn đá thứ nhất rơi tự do từ đỉnh của một toà tháp chiều cao h. Tại thời điểm hòn đá cách đỉnh tháp một khoảng  thì một hòn đá thứ hai bắt đầu rơi tự do tại vị trí cách đỉnh tháp một khoảng . Biết hai hòn đá chạm đất đồng thời. Chiều cao của tháp là        

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose one sentence that has the same meaning as the root one:

  He was accused of stealing a thousand pounds from his employer.
  
  

• Choose the word that has the underlined part pronounced differently from the rest:  

  child                   chill                   wild                   nice

• Choose the word that has the underlined part pronounced differently from the rest:  

  report                  access                   section                      respect

• Choose the word that has the underlined part pronounced differently from the rest:  

  over                  problem                       know                  low

• Choose the word that has the underlined part pronounced differently from the rest:  

  desire                noisy                 sugar                  present

• Choose the word that has the underlined part pronounced differently from the rest:  

  card                    car                     apparent                    part

• Read the following passage and choose the best answer for each blank:

          English is the (1)_________ important in the world today. A very large (2)________ of people understand and use English in many (3)_______ of the world.
          Indeed English is a very useful language. If we (4)______ English we can go to any
  place or country we like. We shall not find it hard to (5)_______ people understand what we want to say.
          English also helps us to learn all kinds of subjects. Hundreds of books are(6)______ in English every day in many countries to teach people many useful  things. (7)_______ English language has therefore helped to spread ideas and knowledge to all the comers of the world. There is no subject that cannot be (8)_______ in English.
          As English is used so much everywhere in the world, it has helped to make the countries in the world more (9)______ . The leaders of the world use English to
  understand one another. The English language has therefore helped to spread better understading and friendship among countries of the world.
          Lastly, a person who knows English is respected by people. It is for all these (10) _________ that I want to learn English.

   

  1. A. most	B. mostly	C. chiefly	D. best
  2. A. few	B. deal	C. amount	D. number
  3. A. countries	B. places	C. sites	D. scenes
  4. A. realize	B. say	C. speak	D. tell
  5. A. get	B. let	C. persuade	D. make
  6. A. published	B. wrote	C. print	D. made
  7. A. A	B. An	C. That	D. The
  8. A. recognized	B. realized	C. known	D. taught
  9. A. friend	B. friendly	C. friendship	D. friendliness
  10. A. reasons	B. causes	C. effects	D. results

• Choose the correct sentence which is built from the words and phrases given:

  Although / parents / busy / work/ try / spend / much / time / children / possible //.

• Choose the correct sentence which is built from the words and phrases given:

  American / be / more / concern / Chinese / physical / attractiveness / when / choose / wife / husband //.

• Choose the correct sentence which is built from the words and phrases given:

  Prepare / job / interview / can / stressful / particular / when / you / call / first / one //.