问题
选择题
蝌蚪发育成青蛙的过程中，先后出现呼吸器官的顺序是（ ）
A．外鳃→内鳃→肺
B．内鳃→外鳃→肺
C．肺→外鳃→内鳃
D．内鳃→肺→外鳃
答案
青蛙的生殖发育过程是：受精卵、蝌蚪、幼蛙、成蛙．幼体生活在水中，用鳃呼吸，蝌蚪的外鳃退化再长出内鳃，成体生活在水中，也能生活在陆地上，主要用肺呼吸，幼体和成体在形态结构上相差很大，为变态发育．
故选：A
搜题请搜索小程序“爱下问搜题”
蝌蚪发育成青蛙的过程中，先后出现呼吸器官的顺序是（ ）
A．外鳃→内鳃→肺
B．内鳃→外鳃→肺
C．肺→外鳃→内鳃
D．内鳃→肺→外鳃
青蛙的生殖发育过程是：受精卵、蝌蚪、幼蛙、成蛙．幼体生活在水中，用鳃呼吸，蝌蚪的外鳃退化再长出内鳃，成体生活在水中，也能生活在陆地上，主要用肺呼吸，幼体和成体在形态结构上相差很大，为变态发育．
故选：A
Professor Green, known to the world as a scientist, is not only absent-minded but short-sighted as well. His mind is always busy scientific problems and seldom notices what is going on him. One fine day recently, he went a walk in the countryside, but as he has a book in his hand. When he went out , he began to read his book . He hadn’t gone far he run into a big cow and fell down. In the fall, he had lost his glasses, without which he couldn’t see anything. He thought he had hit his head a fat lady. “I’m sorry, Madam.” He said politely searching for his glasses. As soon as he had , he realized his mistake. Soon he was fixing his mind on his book and paid no attention to anything else. He had scarcely been walking for five minutes when he fell over again, both his book and his glasses. This time he got very angry, seizing his umbrella, he gave the “cow” a wild blow. Then, after finding his glasses, he realized with horror that he made a second mistake. A large fat woman was fleeing from him in a horror.
|