If I had remembered （ ） the window, the thief would not have got in.

The twin sisters look so much alike that I could never tell _____.

Her （ ） to the job left her with very little free time．

The two boys had so _____ in common that they soon became good friends.

I stayed up all night _____ to find a new solution to the problem.

The doctor said that mental （ ） is the major cause of his sleeping problem.

Thank you for your letter of May 6, in which you _____ about the bicycles of Model 897.

You needn’t introduce him to me. I’ve met him on several _____.

It is （ ） impossible to work with this noise around.

（ ） has already been pointed out before, English grammar is not a set of dead rules.

（ ） comes back first is supposed to win the prize.

Many students thought about the third question for quite a while and had great difficulty answering it. Obviously, it was _____ all.