题目

根据短文内容，从方框中选择恰当的单词填空，每个单词只能用一次，每空一词。 terrible nothing first times shy chose chances When happily win Life is not easy, so I'd like to say, When anything happens, believe in yourself.When I was a young boy, I was too to talk to anyone. My classmates often laughed at me. I was sad but could do . Later, something happened, and it changed my life. It was an English speaking contest. My mother asked me to join in it. What a idea. It meant I had to speak in front of all the teachers and students of my school!C20．如图是人体内的气体交换过程示意图，据图分析回答下列问题：（1）从图中可看出人体内的气体交换包括[A]肺泡与血液的气体交换和[B]血液与组织细胞的气体交换两个过程．（2）图中①表示氧气，②表示二氧化碳，①和②交换的原理是通过气体扩散作用实现的．（3）气体进出肺泡是通过呼吸运动来实现的．