He felt that there __ something wrong about it.
A.is
B.have
C.must be
D.must have
答案:C
根据岩石成因可将组成地壳的岩石分为岩浆岩、沉积岩、变质岩。
机组冷态启动时,投入5%启动旁路,发电机并网后,可不关闭5%启动旁路电动门。()