15. (A)he spilled his drink onto the floor 　　(B)he has just finished wiping the floor 　　(C)he was caught in a shower on his way home 　　(D)he rushed out of the bath to answer the phone

18. (A)The building of the dam needs a large budget 　　(B)the proposed site is near the residential area 　　(C)the local people fel insecure about the dam 　　(D)the dam poses a threat to the local environment 　　Question19 to21 are based on the conversation you have just heard