21. –I think you’d better type this letter again before Mr. Smith see it. -- Oh, dear! 　　　(A) Who cares? (B) No problem 　　　(C) I don’t mind at all (D) Is it as bad as that?

31. It was announced that only when the fire was under control ___ to return to their homes. 　　　(A) the residents would be permitted 　　　(B) had the residents been permitted 　　　(C) would be residents be permitted 　　　(D) the residents had been permitted 　　　