问题
选择题
This machine is very easy ________. Anybody can learn to use it in a few minutes.[ ]
A. operating
B. to be operating
C. operated
D. to operate
答案
答案：D
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This machine is very easy ________. Anybody can learn to use it in a few minutes.[ ]
A. operating
B. to be operating
C. operated
D. to operate
答案：D