治疗便秘的非处方药
低张力性便秘
A．乳果糖B．硫酸镁C．甘油栓D．比沙可啶E．聚乙二醇粉
参考答案：C
He helps me ____ with my English. [ ]
A. a lot
B. a lot of
C. lots of
D. lot of
做石油分馏实验时，水银温度计的水银球应插入蒸馏液体中。( )
