五、介词：常用介词：in, on, at, behind等
1.at表示时间概念的某一个点。(在某时刻、时间、阶段等)。
at 1：00(dawn，midnight，noon)在一点钟(黎明、午夜、中午)
2.on
1)表示具体日期。
注：(1)关于"在周末"的几种表示法：
at(on)the weekend在周末---特指
at(on)weekends在周末---泛指
over the weekend在整个周末
during the weekend在周末期间
(2)在圣诞节，应说at Christmas?而不说on Christmas?
2)在(刚……)的时候。
On reaching the city he called up his parents.
一到城里他就给父母打了一个电话。
3.in
1)表示"时段"、"时期"，在多数情况下可以和during互换，前者强调对比，后者强调持续。 in(during)1988(December，the 20th century)在一九八八年(十二月、二十世纪)
六、动词：动词的四种时态：
(1)一般现在时：
一般现在时的构成
1. be动词：主语+be(am, is, are)+其它。如： I am a boy. 我是一个男孩。
2. 行为动词：主语+行为动词(+其它)。 如： We study English. 我们学习英语。
当主语为第三人称单数(he, she, it)时，要在动词后加"-s"或"-es"。如：Mary likes Chinese.玛丽喜欢汉语。
动词+s的变化规则
1.一般情况下，直接加-s，如：cook-cooks, milk-milks
2.以s. x. sh. ch. o结尾，加-es，如：guess-guesses, wash-washes, watch-watches, go-goes
3.以“辅音字母+y”结尾，变y为i, 再加-es，如：study-studies
(2)一般过去时:
动词过去式详解 动词的过去式的构成规则有：
A、规则动词
① 一般直接在动词的后面加ed：如 worked , learned , cleaned , visited
② 以e结尾的动词直接加d：如 lived , danced , used
③ 以辅音字母加y结尾的动词要改y为i再加ed(此类动词较少)如 study – studied carry – carried worry – worried (注意play、stay不是辅音字母加y,所以不属于此类)
④ 双写最后一个字母(此类动词较少)如 stopped
B、不规则动词(此类词并无规则，须熟记)小学阶段要记住以下动词的原形和过去式：sing – sang , eat – ate ,
see – saw , have – had , do – did , go – went , take – took , buy – bought , get – got , read – read ,fly – flew , am/is – was ,
are – were , say – said , leave – left , swim – swam , tell – told , draw – drew , come – came , lose – lost , find – found , drink – drank , hurt – hurt , feel – felt
(3)一般将来时：
基本结构：
①be going to + do;
②will+ do. be going to = will
I am going to go swimming tomorrow(明天). = I will go swimming tomorrow.
(4)现在进行时: am,is,are+动词现在分词
动词现在分词详解 动词的ing形式的构成规则：
① 一般的直接在后面加上ing , 如doing , going , working , singing , eating
② 以e 结尾的动词，要先去e再加ing ，如having , writing
③ 双写最后一个字母的(此类动词极少)有：running , swimming , sitting , getting