题目

______ the police thought he was the most likely one, since they had no exact proof about it, they could not arrest him. A. Although     B. As long as   C. If only D. As soon as 答案：A 解析: 考查从属连词的用法。根据句意，引导让步状语从句。故选A。设函数f（x）=|x|x+bx+c，则下列命题中正确命题的序号有     （请将你认为正确命题的序号都填上）①当b＞0时，函数f（x）在R上是单调增函数；②当b＜0时，函数f（x）在R上有最小值；③函数f（x）的图象关于点（0，c）对称；④方程f（x）=0可能有三个实数根．