细粒棘球蚴终宿主主要是（）
A.羊
B.狗
C.猫
D.牛
E.猪
参考答案：B
I’ve got a message from the head teacher ______ the English exam won’t be held tomorrow.
A．why
B．whether
C．that
D．which
甘草次酸的结构类型是
A．甾体
B．三萜
C．二萜
D．二氢黄酮
E．二氢黄酮醇
