属于肠道原虫的是（）
A.蛔虫
B.鞭虫
C.钩虫
D.蛲虫
E.蓝氏贾第鞭毛虫
参考答案：E
The girl is an excellent student but not once in these years________ caught being late.
A．has she got
B．she has been
C．was she
D．she got
甾体皂苷苷元是由多少个碳原子组成（）
A.29
B.27
C.31
D.25
E.22
