从下面选项中选择正确答案；单击“核对答案”按钮，核对你的答案.

1 :  When we were children, we __________ tidy our rooms before we could watch TV.

2 :  Now I have a good salary, I __________ worry about paying the rent.

3 :  Which sentence has the strongest obligation?

4 :  You __________ use a video camera to record films while you are in the  cinema. It's illegal.

5 :  For us, the ideal house __________ have three bedrooms but it __________ have  a big kitchen. Kitchens aren't very important for us as we rarely cook.

6 :  The doctor says he __________ be careful about his weight and diet because he  has a history of heart disease in his family.