Sincewehaveafocusedsubject，weshouldnottalk________.
A、atonceD
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。
The professor worked for 7 hours at a ________.
_______,couldyougetmeaTurkishconversationbook?
Sincewehaveafocusedsubject，weshouldnottalk________.
Although Tom is satisfied with his academic achievement，he wonders _______ will happen to his family life .
A year later，with the nation’s economy ________，Bush’s approval rating dropped below 40 percent
