下午6时整，时针和分针所组成的角是______角．
下午6时整，钟面上的时针和分针成180度的角，叫作平角；
故答案为：平．
After ________________ a sandstorm warning on Sunday evening, meteorologists forecast that dusty weather will continue in parts of the country on Monday.
A．breaking off
B．calling off
C．leaving off
D．putting off
逆变角过小会导致（）
A.出发信号功率小
B.触发信号宽度窄
C.整流输出电压低
D.逆变失败
