发芽马铃薯含有的有毒物质是（）

A.龙葵素

B.皂素

C.植物血凝素

D.氰苷

E.类秋水仙碱

            who had arrested him three times for drug-taking.

A．Before George stood the policeman

B．Before George the policeman stood

C．Before the policeman stood George

D．Stood before the policeman George