亮度鉴别实验表明,韦伯比越大,则亮度鉴别能力越()
参考答案:差
– Bad luck! The car breaks down again. I wish I knew about car repair.
________ you learn? Courses are offered at Seamine College.
________. I wonder when courses begin.
A.Why don’t; That’s a good idea
B.Did; That’s reasonable
C.Why don’t; I don’t care for it
D.Did; Your idea sounds very encouraging
隔离开关与断路器串联安装使用时,拉闸顺序是()。
A.先断开刀开关后断开断路器
B.先断开断路器后断开刀开关
C.同时断开断路器和刀开关
D.无先后顺序要求