2. 职称英语
  3. Dung beetles ______ an integral part of the successful management of diary farms

Dung beetles ______ an integral part of the successful management of diary farms

游客2023-11-09  49
问题 Dung beetles ______ an integral part of the successful management of diary farms in Australia over the past few decades.
选项 A、has become
B、have become
C、became
D、had become
答案 B
解析 时态题。在由until(till，up to)now，up to the present，so far，in (for，over，during)the past(last，recent)few(several，two．．．)months(days．．．)等构成的短语作状语的句子中常用现在完成时。主语dung beetles复数形式，故B正确。
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