表示时态的特殊方法
1.used to / be used to  used to + do："过去常常"表示过去习惯性的动作或状态，但如今已不存在。例如： 
Mother used not to be so forgetful. 老妈过去没那么健忘。 
Scarf used to take a walk. 斯卡夫过去常常散步。 

be used to + doing：对……已感到习惯，或"习惯于"，to是介词，后需加名词或动名词。例如： 
He is used to a vegetarian diet. Scarf is us ed to taking a walk. 斯卡夫现在已习惯于散步了。

人称代词有两类，一类主格一类宾；主格代词本领大，一切动作由它发；宾格代词不动脑，介动之后跟着跑。

2. be to和be going to be to 表示客观安排或受人指示而做某事，be going to 表示主观的打算  或计划。初中英语语法练习题例如： 
I am to play football tomorrow afternoon. 明天下午我去踢球。（客观安排） 
I'm going to play football tomorrow afternoon. 明天下午我想去踢球 。（主观安排）

3.用现在进行 时表示将来
下列动词come, go, arrive, leave, start, begin, return等现在进行时可以表示将来。例如： 
a.I'm leaving tomorrow. 明天我要走了。 
b.Are you staying here till next week? 你会在这儿呆到下周吗？

4. 比较since和for
Since  用来说明动作起始 时间，for用来说明动作延续时间长度。例如： 
I have lived here for more than twenty years.我住在这儿二十多年了。 
I have lived here since I was born. 我从出生起就住在这儿了。 

注意：并非有for 作为时间状语的句子都用现在完成时。 
I worked here for more than twenty years. （我现在已不在这里工作。） 
I have worked here for many years.（现在我仍在这里工作。） 

注意：用句型转换的方法，很容易排除非延续动词在有for/since结构的完成时中的英语记单词方法误用。 
1）（对） Tom has studied Russian for three years. = Tom began to study Russian three years ago, and is still studying it now. 
2）（错） Harry has got married for six years. = Harry began to get married six years ago, and is still getting married now. 显然，第二句不对，它应改为 Harry got married six years ago. 或 Harry has been married for six years.

5. 延续动词与瞬间动词
1） 用于完成时的区别 延续 动词表示经验、经历； 瞬间动词表示行为的结果，不能与表示段的时间状语连用。例如：  
He has completed the work. 他已完成了那项工作。 （表结果） 
I've known him since then. 我从那时起就认识他了。（表经历）

2） 用于till / until从句的差异 延续动词用于肯定句，表示"做……直到……" 瞬间动词用于否定句，表示"到……，才……"。例如： 
He didn't come back until ten o'clock. 他到10 点才回来。 
He slept until ten o'clock. 他一直睡到10点。

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