1.In a large lecture class it's hard to the professor as often as we might like.

2. When you give a speech it's not necessary to the whole passage if you know the key points.

3. In using a foreign language it's good to the meanings of some familiar idioms.

4. I'll find some time to read your paper, but I'm very busy right now.

5. It takes time for a new teacher to the faculty (全体教师) and feel comfortable on the job.