一、单项选择（共15小题；每小题l分，计15分）
从下列各题A、B、C、D四个选项中，选择一个能填入空白处的最佳答案。
1．In the nineteenth century, English became international language．
A．an B．a C．/ D．the
2．— I’m afraid I can’t you, sir．Can you speak more slowly?
— Of course．
A．follow B．listen C．see D．find
3．China began to open to the outside world in the late 1970s．_________, there have been great changes in the country．
A．By then B．As a result C．At last D．In all
