问题
解答题
家鸽的体内有气囊,它的主要作用是进行气体交换.______.
答案
答:家鸽飞行时,当两翼举起气囊扩张,外界的气体进入肺和气囊,在肺内进行一次气体交换.当两翼下垂时,气囊收缩,气囊里的气体进入肺完成第二次气体交换后排出体外,所以每呼吸一次进行气体交换两次,进行气体交换的场所在肺,气囊只是暂存气体的作用.
故答案为:×
家鸽的体内有气囊,它的主要作用是进行气体交换.______.
答:家鸽飞行时,当两翼举起气囊扩张,外界的气体进入肺和气囊,在肺内进行一次气体交换.当两翼下垂时,气囊收缩,气囊里的气体进入肺完成第二次气体交换后排出体外,所以每呼吸一次进行气体交换两次,进行气体交换的场所在肺,气囊只是暂存气体的作用.
故答案为:×
选择下列词汇完成下面对话。(共5小题,每小题1分)
B: Yes. I want to buy a skirt. A: This小题1:__________ please. All our skirts are in this section. How do you like the red one here? B: It looks nice, but I don't like red. It小题2:__________ very hot. A: Do you like white? There is also a white小题3:__________. B: I think that's what I want. How小题4:__________ is it? A: It's sixty-six yuan. B: How about fifty yuan? A: Hmm, 小题5:_________ you like it so much, you can take it with fifty-five yuan. That's the lowest price I can offer. B: That's good! I'll take it. |