问题
A large amount of solar energy ________ electrical energy since amounts of advance equipment ________ introduced.
A:was converted into were
B:were converted into was
C:have been converted into wasDhas been converted into were
D:has been converted into were
B:were converted into was
C:have been converted into wasDhas been converted into were
D:has been converted into were
正确答案是：
同类题型
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