含有毒双酯类生物碱的药材是
A.天麻
B.延胡索
C.川乌
D.黄芪
E.石菖蒲
参考答案:C
解析:川乌的化学成分含生物碱,其中主要为剧毒的双酯类生物碱(乌头碱、中乌头碱、次乌头碱等)。
—When did he work_______the railroad?
—From 1904 to 1909. [ ]
A. in
B. on
C. at
D. of
He had to put his shoes lightly, _____ he? [ ]
A. didn't
B. did
C. had
D. hadn't