从每小题的A．B．C．D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该选项涂黑。
1．Annoyed by the salesman's bad manners, John chose of the two computers on sale and left．
A．all B．either C．neither D．none
2．---Tom has been fired by his boss．
--- ? As far as I know, he is a hardworking and considerate fellow．
A．Why not B．How come C．What then D．So what
3．I was chatting on the Internet last night when I smelt something in the next room．
A．burning B．to burn C．be burnt D．to be burnt
4．The policeman scolded the driver for turning without a ．
A．symbol B．mark C．signal D．chance
