为保证药效，血药浓度应达到病原菌最低抑菌浓度的（）
A.12倍
B.15倍
C.2～10倍
D.3／2倍
E.1／10～1／2倍
参考答案：C
I had to call a taxi because the box was ______ than I’d expected.
A．heavy
B．heavier
C．the heavier
D．the heaviest
用板牙套一公称直径为d、螺距为P的螺纹，圆杆的直径选取为（）。
A.d
B.d-1p
C.d-0.13p
D.d-0.2p
