问题
选择题
The great invention he made ___ of great benefit to the whole world.[ ]
A. is proved
B. has proved
C. has been proved
D. is proved to be
答案
答案：B
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The great invention he made ___ of great benefit to the whole world.[ ]
A. is proved
B. has proved
C. has been proved
D. is proved to be
答案：B