. If you think that the illness might be serious, you should not ______ going to the doctor.

. The boy was sitting at the desk, ______ hard when his mother got home.

If you ______ half an hour every day for English reading, you are sure to improve your reading ability.

Some parents are just too protective. They want to_________their kids from every kind of danger, real or imagined. 

．People have planted a lot of trees and grass in order to ____ wind and sand in the desert．

The managers discussed the plan that they would like to see _______the next year.

. The president spoke at the business meeting for nearly an hour without ___ his notes.

Bill, often regarded as one of the best students in his class, ____ to be the student who cheated in the exam.

A study shows that students living in non-smoking dormitories are less likely to ________ the habit of smoking.  

—Jack, this is the third time that you have been late this week．
—Sorry, sir, but I was_____ for 15 minutes on the way here in the traffic jam．