Question

【题目】For years scientists have been worried about the ______ of air pollution on the earth's natural conditions.

A. effect B. result

C. account D. cause

Answer 1

【答案】A

【解析】句意：许多年里,科学家们一直担心空气污染对自然环境造成的影响。考查名词辨析。effect“影响”，符合题意。result “结果”; account “记述；账户；解释”; cause “原因”。