泡沫混合液管道涂那种颜色()
A、红色
B、黑色
C、黄色
D、绿色
参考答案:A
一 Where have you been all day?
— I _____ some former classmates and I couldn't get back until it was dark. [ ]
A. have met
B. met
C. would meet
D. had met
220kvGIS设备SF6气体的额定年泄漏率应≤()﹪。