1.after a week 经常放在叙述过去的事情中,因此用过去式.如：The boy didn't go to school because of his illness.After a week,his teacher came to see whether he was better.
2.as soon as 表示一.就 如：I will lend the book to you as soon as I have finished reading it.
when 有两个意思.一 为“当.时候” When I was a child,I often went to the nearby library at weekends.
一为“ 就在那时” I was about to leave when someone phoned me .
3.other 是单数,一般不单独出现,常和the 连用,表示一个范围内的另一个,如：I have two apples.One is big and the other is small.
others指他人,如：Leifeng was always ready to help others.
another 指三个或三个以上的另一个,如：I have three balls.One is red,another is blue,and the other/ the rest isyellow.
4.It is / was +被强调的部分（主语,表语,宾语或状语） + that + 其他
如：原句为 I saw Mary in the street yesterday
可以改为：It was I that saw Mary in the street yeaterday.
It was Mary that I saw in the street yesterday.
It was in the street that I saw Mary yesterday.
It was yesterday that I saw Mary in the street.
5.keep up one's mind on 指使自己的心思放在.上
make up one's mind 指下定决心做.