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We________ on it for several hours, but we have not yet found any satisfactory solution.
分类:
学位英语(x0001)
发表:2024年07月31日 06时07分27秒
作者:
admin
阅读:
(16)
We________ on it for several hours, but we have not yet found any satisfactory solution.
A、 are working
B、 have been working
C、 have been worked
D、 work
【正确答案】:B
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