21. Seldom() any mistakes during my past five years of service here.

A. made I √B. did I make C. should I make D. would I make

22. So little () that the meighbors couldn’t settle their differences.

√A. did the agree B. agree did they C. they agree D. they did agree

23. They thought it() question to ask.

A. too difficult B. a too difficult

C. too a difficult √D. too difficult a

24. “Have you ever seen any thing like that before?” “No, () .”

A. I never have seem anything like that before

B. never I have seen anything like that before

√C. never have I seen anything like that before

D. I have seen anything like that before