It is that he has been addicted to the drugs and has difficulty quitting it.A. obviouslyB

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：考查句型：It is likely that 很可能…，likely 形容词，可能的，A、B、C为副词，意思分别为显然地、明显地、可能地。此题应用形容词，所以选D。