按目前国家规定,工作面回收率,薄煤层不低于93%,中厚煤层不低于95%,厚煤层不低于97%。
参考答案:错
people were found after the Wenchuang earthquake.
A.A number of; died
B.The number of; died
C.A number of; dead
D.The number of; dead
功率因数在数值上是有功功率和无功功率之比。