Pigeons have been used as messengers because ______. A: they have a built-in compass B: they can cover 500 miles in a single day C: they have special ability to tell directions D: they can find their way home
Pigeons have been used as messengers because ______. A: they have a built-in compass B: they can cover 500 miles in a single day C: they have special ability to tell directions D: they can find their way home
Which of the following is not an accurate statement? A: Hormones are chemical messengers that travel to target cells through the circulatory system B: Hormones often regulate homeostasis through antagonistic functions C: Hormones of the same chemical class usually have the same function D: Hormones are often regulated through feedback loops
Which of the following is not an accurate statement? A: Hormones are chemical messengers that travel to target cells through the circulatory system B: Hormones often regulate homeostasis through antagonistic functions C: Hormones of the same chemical class usually have the same function D: Hormones are often regulated through feedback loops
四级选词阅读理解-muscle performance 四级选词填空阅读理解 考查的知识点：1.考生对词性的把握，如不定冠词(a)、介词(of)、形容词后跟名词;2.常用短语3.时态运用；4.逻辑衔接表达，如指代(such)，递进(also)、转折(conversely)等的理解。 考生应在结合上下文理解句意的基础上进行综合作答，注意词性正确、常用短语搭配、动词时态、前后逻辑对应等。 请在把单词前面的大写字母填入答案处。 A) cautiously I) phenomenon B) commit J) preventing C) control K) sensitive D) cycling L) slowing E) effectively M) solution F) increased N) sufficient G) involved O) vigorous H) limited As if you needed another reason to hate the gym, it now turns out that exercise can exhaust not only your muscles, but also your eyes. Fear not, however, for coffee can perk them right up again. During （1）exercise, our muscles tire as they run out of fuel and build up waste products. Muscle performance can also be affected by a (2) called "central fatigue," in which an imbalance in the body's chemical messengers prevents the central nervous system from directing muscle movements (3) . It was not known, however, whether central fatigue might also affect motor systems not directly (4). in the exercise itself—such as those that move the eyes. To find out, researchers gave 11 volunteers a carbohydrate (5) either with a moderate dose of caffeine—which is known to stimulate the central nervous system—or as a placebo without, during 3 hours of (6) . After exercising, the scientists tested the cyclists with eye-tracking cameras to see how well their brains could still (7) their visual system. The team found that exercise reduced the speed of rapid eye movements by about 8%, (8) their ability to capture new visual information. The caffeine—the equivalent of two strong cups of coffee—was (9) to counteract this effect, with some cyclists even displaying ( 10) eye movement speeds, the team reports today in Scientific Reports. So it might be a good idea to get someone else to drive you home after that marathon.
四级选词阅读理解-muscle performance 四级选词填空阅读理解 考查的知识点：1.考生对词性的把握，如不定冠词(a)、介词(of)、形容词后跟名词;2.常用短语3.时态运用；4.逻辑衔接表达，如指代(such)，递进(also)、转折(conversely)等的理解。 考生应在结合上下文理解句意的基础上进行综合作答，注意词性正确、常用短语搭配、动词时态、前后逻辑对应等。 请在把单词前面的大写字母填入答案处。 A) cautiously I) phenomenon B) commit J) preventing C) control K) sensitive D) cycling L) slowing E) effectively M) solution F) increased N) sufficient G) involved O) vigorous H) limited As if you needed another reason to hate the gym, it now turns out that exercise can exhaust not only your muscles, but also your eyes. Fear not, however, for coffee can perk them right up again. During （1）exercise, our muscles tire as they run out of fuel and build up waste products. Muscle performance can also be affected by a (2) called "central fatigue," in which an imbalance in the body's chemical messengers prevents the central nervous system from directing muscle movements (3) . It was not known, however, whether central fatigue might also affect motor systems not directly (4). in the exercise itself—such as those that move the eyes. To find out, researchers gave 11 volunteers a carbohydrate (5) either with a moderate dose of caffeine—which is known to stimulate the central nervous system—or as a placebo without, during 3 hours of (6) . After exercising, the scientists tested the cyclists with eye-tracking cameras to see how well their brains could still (7) their visual system. The team found that exercise reduced the speed of rapid eye movements by about 8%, (8) their ability to capture new visual information. The caffeine—the equivalent of two strong cups of coffee—was (9) to counteract this effect, with some cyclists even displaying ( 10) eye movement speeds, the team reports today in Scientific Reports. So it might be a good idea to get someone else to drive you home after that marathon.