Question

Don’t turn off the computer before closing all programs，________ you could have problems.                                                          (2013·北京，22)

A．or	B．and
C．but	D．so

Answer 1

　A
解析　考查连词用法。句意为：关闭所有程序后再关电脑，否则会有麻烦的。or否则，要不然，用于警告或忠告。