烟草中主要的致癌物质是（）

A.尼古丁

B.烟焦油

C.重金属

D.醛酸类

E.吲哚吡啶

Li Ming made great progress ________ of his parents.[ ]

A．to their much delight

B．to the much delight

C．to much delight

D．much to the delight