用含有某种激素的饲料喂养蝌蚪，能缩短蝌蚪发育成成蛙的时间，饲料中所含激素是（ ）
A．生长激素
B．胰岛素
C．肾上腺素
D．甲状腺激素
甲状腺激素是由甲状腺分泌的，它的主要作用是促进新陈代谢、促进生长发育、提高神经系统的兴奋性；用含某种激素的饲料喂蝌蚪，能缩短蝌蚪发育成蛙的时间，说明该激素能够促进蝌蚪的生长发育，因此这种激素应该是甲状腺激素；生长激素是由垂体分泌的，有调节人体生长发育的作用；胰岛素的作用是调节血糖在体内的吸收、利用和转化等，如促进血糖合成糖元，加速血糖的分解等；肾上腺皮质激素的作用是调节动人体内的水盐代谢和糖代谢．故D符合题意．
故选：D．
| 完形填空。 Around the world, people have different ideas about what good manners are. When you go to restaurants in different parts of the world, it's 1 to know the right and wrong things to do. For example, in China it's OK to 2 a lot of noise in a restaurant. In fact, if a restaurant isn't noisy and 3 , you may think there's something wrong with it. However, in many western countries, restaurants are 4 places. If a table is too loud, other people who are eating there might even 5 to the owner of the restaurant. Paying the bill is also different from country to country. In China, one person usually pays for 6 . In western countries, one person pays if he or she is entertaining clients, but 7 friends eat together, they usually share the cost. This is called "Going Dutch. "Also, when westerners pay the bill, they usually leave some money for the 8 . This is called "leaving a tip". Leaving a tip is thought to be polite. In the USA, it's 9 to leave tips of 10%, 15%, or 20% of the bill, which is decided by how good the service is. Good waiters can make a lot of money! The way people eat food is different in the world, but you can 10 the same kinds of food in many countries. Chinese and Italian food, for example, are popular all over the world. | |||
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