题目

补全下面的对话。A. duck B. monkey C. Cool D. dog E. birdA: What's this?B: Is it a ?A: No! It's aB: What's that?A: Is it a ?B: No! It's aA:! I like it. 答案：【1】D【2】A【3】E【4】B【5】C小鸟孵卵并精心喂食杜鹃的雏鸟。对小鸟的这种行为的解释，正确的是（　　） ①是先天性行为②是学习行为③是由遗传物质决定的④是环境因素决定的。A. ①③ B. ②④ C. ①④ D. ②③