对100个某种产品进行寿命测试,在t=100h前磨牙失效。100~105有1个失效,失效率为()
A.0.1%/h
B.0.2%/h
C.0.4%/h
D.0.8%/h
参考答案:B
There is ________ to their building from the main street, so you have to go round about.[ ]
A. no issue
B. no content
C. no alternative
D. no access
肉桂扩张血管,增加冠脉和脑血流量作用的有效成分()
A、乙酸苯丙酯
B、桂皮醛
C、多糖
D、肉桂苷
E、香豆素