在安装变压器时,应沿瓦斯继电器方向有()升高坡度。
A.1%
B.1%—1.5%
C.3%
参考答案:B
The bell is ringing. Hurry up, _______ you'll be late for class! [ ]
A. and
B. but
C. while
D. or
《水质挥发酚的测定蒸馏后4-氨基安替比林分光光度法》(GB/T7490-1987)的最低检出浓度为()mg/L,测定上限是()mg/L,