Without facts , a person can’t form a correct opinion , for he needs to have actual knowledge          his thinking .

You should try to get a good night’s sleep _______ much work you have to do.

Ｉdidn’t go to bed _______ I finish my homework.

This is the museum ___ we visit yesterday.

I often think of the years ____ I worked with the foreigners, ____ has had a great effect on my later life.