1.up to 忙于;目的是...
例句:What are they up to?
他们安的是什么心?
2.lock up 关闭;封锁
例句:Don't forget to lock up when you leave.
你离开时不要忘记上锁。
3.mend one's ways 使...改邪归正
例句:He was determined to mend his ways and turn over new leaf.
他决心改过自新,重新做人。
4.one at a time 一次一个
例句:Wouldn't it taste better if you bought one at a time?
如果你一次买一杯,味道不是更好些吗?