重点讲解：
1. ask sb. sth.
询问某人某事；
eg. I asked him his name.
我询问了他的名字。
eg. Hey, can I just ask you something?
嘿，问你点事好吗？
2. back up
备份（文件）；
eg. Make a point of backing up your files at regular intervals.
一定要定期备份文件。
eg. I get so annoyed when I lose work because I've forgotten to back it up.
当我因为忘了备份把完成的工作弄丢时，真是懊恼极了。
3. I can't tell you
（用来强调所说的话）我没法形容……
eg. I can't tell you how glad I was to leave that place.
我无法形容自己离开那个地方心里有多高兴。
eg. We have a lot of work to do, and I can't tell you how happy I am that we've finally, finally got to this point.
我们有许多工作要做，我们最终获胜，我难以表达我有多么高兴。
4. appreciate sb. doing
感谢某人做某事；
eg. I really appreciate you coming over to help me with my math.
我真的很感谢你过来帮我补习数学。
eg. Please contact me with any questions, and I appreciate you taking the time to look.
如有任何问题请联系我，感谢您抽出时间看。
5. on short notice
忽然，急忙；
eg. We had to set out on short notice.
一接到通知，我们就出发了。
eg. Although I had been invited to the opening ceremony, I was unable to attend on such short notice.
虽然我已经被邀请参加开幕式，但是时间这么仓促我还是没能去成。