21 Usually children are allowed to ___________ when they are six years old.
A. attend school B. attend the school C. join school D. join the school
22. Professor Hawking stepped into the office I knew that there was no hope.
A. Unless B. Now that C. Although D. The moment
23. —I'm terribly sorry that I failed to win the game.
—You are not ________ for all you could do.
A. to blame B. pleased C. right D. satisfied
