一般的断路器的动作时间为0.06-0.15s,最快的可达()。
A、0.06-0.15s
B、0.02-0.06s
C、0.06-0.12s
D、0.01-0.04s
参考答案:D
We go to school _____ Monday _____ Friday. [ ]
A. from, in
B. from, to
C. from, at
呕血与黑便最常见的疾病是( )
A.十二指肠炎B.慢性胃炎C.急性胃黏膜病变D.消化性溃疡E.胃底、食管静脉曲张破裂