If you go into a store and feel that the clerk is being rude, stop and think that she____ a tough day, and put yourself in her shoes. 

It is demanded that the plan _____ out as soon as possible. 

 But for friction (摩擦力), people ______ neither walk, nor even stand up.

Regulations require        needs special diets         the cooking manager in advance.

Mr. Smith insisted that his book _______within three days.