题目

Great changes _________ in my hometown and a lot of factories ___________.  A. have been taken place; are being set up  B. have taken place ; have been set up  C. are taken place ; had been set up  D. had taken place; will be set up 答案：B能卷舌和不能卷舌是一对相对性状，分别由A和a控制，下列叙述中不正确的是A、显性基因控制的性状可以表现出来B、隐性基因控制的性状不能表现出来C、能卷舌的基因组成不一定是AAD、不能卷舌的基因组成一定是aa