1）I think he will be back in a week．
2）He said he would call on you in a week．
after1）用于将来时，后接时间的一点。例：
①He will come back after ten o’clock．
②I’ll meet you after school today．
2）用于过去时，后既可接时间的一点也可接时间的一段。例：
①He went to Shanxi two weeks ago，and came back after a week．两周前他去了山西，一周后他回来了。
②After liberation，he died of illness．解放后，他病故了
①代词it代替上文提到的单数同一事物，可数名词（例句1））和不可数名词（例句2））都可指。例：
1）I saw a new film yesterday．It’s very instructive．
2）Oceania is a separate landmass，but it is separated from Asia byvery shallow water．
②代词one（s）用来代替同类事物，不一定是同一物，多有前置定语（如例1，3，5）或后置定语（如例4），one代替单数名词（如1，2，4），表示泛指，the one（s）则表示特指（例4，5）。例如：
1）It was exactly like your necklace but it was a different one．
2）You have no watch now，so I think you’d better get one．
3）Will you please pass me some apples？I’d like big ones．
4）Is this university the one they visited last spring？
5）However，new shoots of bamboo will come up from around theroots of the old ones．
③代词that可用来代替前面提到的单数，可数或不可数名词（例1，2）。但这一名词在第一次出现时须有后置定语，以区别于第二次所指之物。当前面提到的是复数名词，则后面要用those代替（例3）。例如：
1）Tom’s textbook is not so new as that of Rose．
2）It was said that the grain output of 1996 was double that of1994．
3）The lights in your classroom are much brighter than those inours．
by sea/by water/by land/by air/by bike/by spaceship
on horseback on（by）the 9 o’clock train．我将乘九点钟的火车去。
on their bikes on（in） a plane
on在上面，如马和自行车，in 在里面，如飞机，火车
I have two friends．One is a teacher and the other is adoctor．
They have four children．One is a girl，the others areboys
I don’t like this pair of shoes．Would you please showme another pair？
Many people are standing there．Some are workers；others are peasants
some time，sometime，some times和 sometimes是常用的几个词，它们形似而含义不同。请记住下面口诀：
分开是“一段”， 相连为“某时”。分开s是“倍、次”， 相连s是“有时”。
读读下面四句话， 便会运用这四个词。例如：
（1）I’ll stay here for some time．我将在这儿呆一段时间。
（2）Kate will be back sometime in February．凯特将在2月某个时候回来。
（3）Our school is some times larger than theirs．我们学校比他们学校大几倍。
（4）Joan goes to school on foot，but sometimes by bike．琼步行上学，但有时也骑自行车去。
so与such都表示“如此的”，“这么，这样”，so用来修饰形容词和副词；而such常用作形容词，用来修饰名词。
该用哪一个冠词，首先要问三个“W”的问题，也就是Which…？ What…？Whose…？
如果答得出来，就用定冠词“the”.如果答不出来，并且这个普通名词是单数可数名词，就用不定冠词“a”
1）Japan is in the east of Asia．
2）Japan is to the east of China．
3）Korea（朝鲜）is on the northeast of China．
“上”和“下”：向（江河）上游用up；向下游用down “北”和“南”：向北用up；向南用down。
“城”和“乡”：向城市用up，向农村或小镇用down。
“来”和“去”：沿着大道来用up，沿着小街走去用down。 “入”和“出”：入校用up，离校down