Since we have a focused subject ，we should not talk ________.
正确答案： D
本题解析：
译文：既然我们已经有了命题， 我们就不应漫无边际地交谈。 此题考查对固定短语的掌握情况。 at once 立刻; at hand在附近，在手头，即将发生; at intervals 间或，不时; at random 随便，任意。
Directions: Translate the following paragraph into Chinese.
Cyberspace,of course. is bigger than a telephone call. It encompasses the millions of personal computers connected by modems-via the telephone system-to commercial online services, as well as the millions more with high-speed links to local area networks, office E-mail systems and the Internet. It includes the rapidly expanding wireless services: microwave towers that carry great quantities of cellular phones and data traffic; communications satellites strung like beads in the geosynchronous orbit; low-flying satellites that will soon crisscross the globe like angry bees, connecting folks too far –flung or too much on the go to be tethered by wires. Someday even our television sets may be part of cyberspace, transformed into interactive “teleputers -called full-service networks like the ones several cable-TV ” by so companies(including Time Warner)are building along the old cable lines, using fiber optics and high-speed switches.
Basically，these attitudes amount to a belief ________ leisure can and should be put to good use
Never before _______ so rapidly developing as it is today．
Anxiety can ________ with children ’s performance at school.