超声波探伤是用于探测焊缝表面缺陷的一种无损检验法。( )
参考答案：错
—I hear a number of workers in the factory______out of work.
—Yes, and the number_____ quite huge.[ ]
A. are; is
B. is; are
C. is; is
D. are; are
功率继电器中属于晶体管功率继电器的型号是（）。
A.LG—11
B.BG4、BG5
C.GG—11
D.LG—11和BG4
