When you finish your work, don’t forget to put the tools back where they _____ .
A. are
B. will be
C. were
D. had been
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When she came out, Mary looked a bit tired because she ______ the house.
A. cleaned
B. was cleaning
C. had cleaned
D. had been cleaning
—Is Tom still not back?— No. By next year he _____ from home for three years.
A. will leave
B. will have been away
C. leaves
D. has been away
The boy was caught cheating in the exam and _____by his headteacher at the moment.
A. was questioned
B. has questioned
C. is being questioned
D. has been questioning
I/O区的寄存器不能直接与PLC外部的输入、输出端子传递信息。
A. 对
B. 错
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