20克体重小鼠灌胃一次给药耐受的最大容量（）。
A.0.8ml
B.0.4ml
C.1.5ml
D.2.5ml
参考答案：A
Jenny is twelve years old. Bob is twenty years old. Bob is ___________ than Jenny. [ ]
A. younger
B. bigger
C. older
用钢尺往返丈量150m的距离，要求相对误差达到1/10000，则往返校差不得大于( )。
A．0.055m
B．0.045m
C．0.025m
D．0.015m
