A-A+
The efficiency of coal－charging machine is very high ______ 1 500 tons of coal per hour.
问题详情
The efficiency of coal-charging machine is very high, ______, 1 500 tons of coal per hour.
A．say
B．saying
C．said
D．to say
请帮忙给出正确答案和分析，谢谢！
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