1.before long 和long before 的区别:
before long 不久以后，很快;long before 很久以前
①They came back before long.
②I knew Tom long before I knew you.
2.be able to与can的区别：
1)be able to 强调通过努力而获得的能力，而can则强调自身已具有的能力。
①She can sing the song in English.
②He will be able to sing this song in English in a few minutes, too.
2)be able to 强调一种结果，而can只强调一种可能。
①Luckily, he was able to escape from the big fire in the end.
②If he got here a few hours earlier, I could save him.
3)be able to 可以有各种时态；而can只有一般现在和一般过去两种时态。
①He is / was / will be able to help you.
②I could help you last night, but you didn’t come.
4) can可用于表示可能性，推测，允许等情况，而be able to通常不这样用。
①You are able to use my pen. (误)
②You can use my pen. (正)
5)can有被动语态，主语为人或物皆可，而be able to只接不定式的主动形式，不接表示被动的不定式，也不可用无生命的名词作主语。
①The work is able to be done by him. （误）
②He is able to do the work.（正）
注意：指过去某时或某个时刻设法做成某事，不用could,而用was\were able to。
I talked with her for a long time,and eventually I was able to make her believe me.
3.facial n.面部护理；美容 a.面部的
①She is having a facial massage.
②I've made an appointment for a facial next week.
4.expression n. 表情，表示，表达，词句，措辞，表现
face n.表面,脸;v.面对,面向 look v.看,寻找;n.看,样子
manifestation n.表现,示威运动 saying n. 谚语,俗话;动词
communication n.交流,通讯 appearance n.出现,露面
countenance n.面容,面部表情;v.赞.. phrase n.短语,习语;vt.措词...
idiom n.成语,惯用语 term n.学期,术语;vt.把 ...
①He had a passive expression on his face.
②The scenery was beautiful beyond expression.
The fire spread through the hotel very quickly but everyone ______ get out．(NMET’97)
A had to B would C could D was able to