（1）变一般疑问句：当句子中有be动词或情态动词时，则把be动词或情态动词(can,could等)提到主语的前面，

　　（口诀：一调二变三问号）;

　　（2）变否定句：在be动词或情态动词后面直接加not变成否定句. (be后not莫忘记)

　　例：①陈述句：She is my sister..

　　疑问句→ Is she your sister?  Yes, I am./ No, I'm not.

　　否定句→ She is not my sister.

　　②陈述句：I can play soccer.

　　疑问句→ Can you play soccer?  Yes,Ican./ No, I can't.

　　否定句→ I can not /can't  play soccer.