Phát biểu nào sau đây sai ?           

An muốn qua nhà Bình để cùng bình đến chơi nhà Cường. Từ nhà An đến nhà Bình có 4 con đường đi, từ nhà Bình tới nhà Cường có 6 con đường đi. Hỏi An có bao nhiêu cách chọn đường đi đến nhà Cường?

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects. For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar. In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

Question: The word “it” refers to_______         

Cho số nguyên dương thỏa mãn . Số hạng không chứa trong khai triển của biểu thức bằng:  

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects. For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar. In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

Question: The word “triggering” is closest in meaning to_________         

Hệ số của số hạng chứa  trong khai triển  bằng:

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects. For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar. In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

Question: Which of the following describes the sequence of color changes that lantana blossom undergo?         

Tập  gồm phần tử . Hỏi có bao nhiêu tập con?  

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects. For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar. In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

Question: The word “haphazard” is closest in meaning to which of the following?             

Tìm hệ số của trong khai triển .

Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects. For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar. In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

Question: The passage implies that insects would be most attracted to lantana blossoms_______