读问句，选择对应的答句。

____①What's the weather like today?            A. No, you can't.

____②Where are my books?                         B. Yes, it is.

____③What time is it?                                   C. It's rainy.

____④Can I wear my new skirt?                      D. It's twelve o'clock.

____⑤Is it cool?                                             E. They're on the bed.

以下情况属于染色体变异的是（）                                     
①唐氏综合征患者体细胞中的第21号染色体有3条
②同源染色体间发生了相应部位的交叉互换       
③染色体数目增加或减少     
④花药离体培养后长成的植株         
⑤染色体上DNA碱基对的增添或缺失