6.在 It‘s time(for sb.)to do sth. It's kind/nice/good of sb. to do sth.

It takes sb. some time to do sth. 的句型中, 动词不定式短语作句子真正的主语.

5.在see,hear,watch,make,let等后面作宾语补足语的动词不定式应省略动词不定式符号“ to”, 但在被动句中, 应添上"to".      

 4.在动词 decide,hope,wish,hate 等动词后应用动词不定式作宾语,而在ask, tell,want,teach 之后则用动词不定式的复合结构,即 “ask sb. to do sth.”的形式

 3.在 keep,enjoy,finish,mind 等动词后采用动词的--ing 形式.      

 1. be busy,what about等后用动词的-ing 形式.  2.在介词后一般应用动词的-ing 形式.          

*3.祈使句中,或在情态动词,助动词后,谓语动词用原形

Don't _____ (read)in the sun , will you?  You'd better _____ (stay)at home since it's raining outside.

 注意所填动词的语态

 Today both basketball and volleyball _________(play) in many countries.        

确定动词的形式

*2.永恒的真理和客观存在的状态用一般现在时.

*1.come,go,leave 等趋向性动词的进行时可用来表示即将发生的动作.

 3.根据主从句的关系来确定时态.           4.根据语言习惯来确定时态

 2.根据上下文来确定时态  

 有些句子没有明显的时间状语,又不能用时态呼应规则来对照,这时就可以根据上下文内容来判断时间关系,确定正确时态. A.Where are the twins?    B.They ______ (go) to visit Uncle Wang.