Question

it's eight clock be watching tv now.

请问英语高手,语法题：
It's eight o'clock now. You ( should) be doing your lessons. You (can't) be watching TV.
这是英语考试的一填空题答案,
1.问为什么 填should与can't ,这两个空是表被动吗?
2.如果没有空格限制,改成It's eight o'clock now.You must do your lessons.You can't watch TV. 句子通不?
3.如果用It's eight o'clock now. You should do your lessons.You can't watch TV. 把句子中的be 与ing 删去,句子在语法上通不?

Answer 1

问题补充：
3.如果用It's eight o'clock now. You should do your lessons.You can't watch TV. 把句子中的be 与ing 删去,句子在语法上通不?
You should do your lessons.你应该去做作业.
You ( should) be doing your lessons. 你本应该正在作作业.
注意区别.
It's eight o'clock now.You must do your lessons.You can't watch TV.
这句是对的.
不过,这是表示命令.MUST.
前面的是SHOULD 表示应该,是责任.
你应该作作业,可你没作.
不是什么被动.