The teacher has a(an) ___________ to get off topic; sometimes it is difficult for students to make out what he is saying.  

You’d better write down the phone number of that restaurant for future      .

 If what you are teaching doesn’t _____ to your students, your students will gradually lose interest in it.

Before the final examination, many students have shown ____ of tension. Some have trouble in sleeping while others have lost their appetite.

David is a skillful worker. I’m sure he has enough _______ to fix all the electronic ______.