F环开环的甾体皂苷元称为( )
A.螺甾烷醇类
B.异螺甾烷醇类
C.呋甾烷醇
D.达玛烷
E.齐墩果烷
参考答案:C
My grandfather is a fat old man _____ a long white beard. [ ]
A. has
B. have
C. with
D. wear
煤气回收的基本条件:在规定的()时间内。