【题目】Conservationists __________on setting aside natural reserves for the wild species they are trying to protect during the past decade.
A.focusedB.focusC.have focusedD.had focused
在线课程【答案】C
【解析】
考查时态辨析。句意:自然保护主义者在过去几十年里一直在致力于为他们尽力保护的野生动物物种留出自然保护区。根据during the past decade，此处应该用现在完成时。故选C。