马桑毒素属于( )
A．单萜B．倍半萜C．二萜D．三萜E．四萜
参考答案：B
解析：[知识点] 萜类的分类
—Did you go to Tom's house for dinner?
—No, I _____.[ ]
A. am not invited
B. wasn't invited
C. haven't invited
D. didn't invite
雪茶功效与作用
