典型心绞痛发作错误的是()
A.体力活动是常见诱因
B.部位在胸骨中上段,界线清楚
C.疼痛可放射至左肩
D.为压榨性疼痛
E.通常持续3~5min
参考答案:B
Not even when _____through the darkest valley _____be afraid, for you are always close beside me.
A.do I walk; will I
B.do I walk; I will
C.I walk ; I will
D.I walk; will I
三相异步电动机按转速高低划分,有()种。
A、2
B、3
C、4
D、5