电器工作于()时,其温升可以达到稳态值。
A.长期工作制
B.短时工作制
C.断续周期工作制
D.ABC均可
参考答案:A
I would have come to your party yesterday but I _______too busy. [ ]
A. was
B. had been
C. would have been
D. am
生产现场中,红色表危险。