⑴ this / that / these / those / last / next / a / every / each等词构成的时间短语,前面不用任何介词。如：Every year travellers from abroad come to visit Pingyao.(每年都有国外的游客来游览平窑镇)/ He had a bad cold that week.(那个星期他患重感冒)

⑵ for有时用来引出动词不定式的逻辑主语,常翻译成"对于…而言"。如：It's too hard for me to finish the work in only one hour.(让我在区区一个小时内完成这项工作太难了)/ The house is big enough for 10 men to live in.(房子够大的可以容10个人住)

⑶ of有时用来表示后面的人物正好是前面的表语的逻辑主语。如：It's very nice/kind of you to do so.(你这么做真是太好了)

⑷ 介词有时会与它的宾语分离,而且宾语前置。

① 当宾语是疑问词时。Who are you talking about?(你们在谈论谁?)

② 宾语在从句中当连接词时。He has a younger brother who he must take good care of.(他有 一个需要他照顾的小弟。) / Do you know who our teacher is talking with over there?(你知道我们的老师在那边和什么人谈话吗?)

③ 动词不定式作定语且该动词为不及物动词,后面有介词。I finally found a chair to sit on.(我 最终找到了一张椅子坐。)