问题补充:
It is that he has been addicted to the drugs and has difficulty quitting it.
A. obviously
B. apparently
C. possibly
D. likely
答案:
A. obviously
B. apparently
C. possibly
(答案→)D. likely
解析:考察形容词作表语。形容词可用在be动词后作表语。副词一般用在实意动词后做状语,句中is后应用形容词作表语,ABC选项都是副词,故只能选D,很可能的,既能做副词,又能做形容词。