21.The ________all demanded to see the manager at once.
   A involving people               B involved people
   C people involving               D people involved

22. — Do you think the Stars will beet the Bulls
—Yes.They have better players, so I _______ them to win.
A.hope         B.prefer             C.expect              D.want

23. They _______ the train until it disappeared in the distance.
A.saw         B.watched           C.noticed              D.observed

24. She _______ his number in the phone book to make sure that she had got it right.
A.looked up    B.looked for          C.picked out           D.picked up

21. 正确答案：D
  例题解析：people involved 意为相关的人， 单个的过去分词作定语一般放于被修饰词后面，

22. 正确答案：C
expect期望.我期望他们赢.hope后面不能接动词不定式作宾补.want想,表示个人的欲望;prefer更喜欢,构成prefer to do sth.,prefer doing sth.to doing sth.,prefer to do sth.rather than do sth.等短语.

23. 正确答案：B
watch注视.他们注视着火车直到它消失在远方.

24. 正确答案：A
look up查找,查寻;look for寻找; pick out挑出来;pick up拾起.她在电话簿是查找电话号码,要用looked up.