We must be careful when we play sports. 变为一般疑问句

问题描述:

We must be careful when we play sports. 变为一般疑问句

We have many friends. They watch TV at 7 in the evening . The 含有行为动词的句子,当主语是第三人称单数时,变一般疑问句要“在原句子的

Must you be careful when you play sports?