The police are to conclude that the cause of fire had been a cigarette end.
A. probable
B. possible
C. maybe
D. likely
网友回答
A. probable
B. possible
C. maybe
(答案→)D. likely
解析：本题考查表“可能”的相关词语的固定搭配。
It is probable that…
It is possible that…
to do…
It is likely that…
to do…
Sb. is likely to do …
由此可见，本题的主语the police 为人，因此应选D。