21. "I don't think it's my ____ that the TV blew up. I just turned it on, that's all,” said the boy.
A. error B. mistake C. fault D. duty
22. --Mum, have you seen my digital camera?
-- _____ you bought last week? I'm afraid I haven't seen
A. The one; it B. The one; one C. One; it D. One; one
23. Our sales ______ for months, so we are now in great financial difficulties.
A. have been dropping B. had been dropping
C. have been dropped D. are dropping
