the police thought he was the most likely one, they could not arrest him since they had no exact proof about it.
A. Although
B. As long as
C. If only
D. As soon as
网友回答
(答案→)A. Although
B. As long as
C. If only
D. As soon as
解析：考查连词：A. Although虽然，B. As long as只要，C. If only 但愿，D. As soon as一…就，句意：虽然警察认为他是最有可能的一个，但是他们不能逮捕他，因为他们没有明确的证据。选A。