三萜皂苷在哪种溶剂中溶解度较大（）
A.丙酮
B.苯
C.乙醚
D.含水正丁醇
E.三氯甲烷
参考答案：D
过抛物线y2=4x的焦点F的一直线交抛物线于P，Q两点，若线段PF的长为3，则线段FQ的长为______．
There are four pairs of socks to _____, but the woman doesn't know _____ to buy. [ ]
A. choose from; which
B. choose from; what
C. choose; which
D. choose; what
