问几个英语语法的问题1.什么时候动词的进行式要双写末字母加ing?2.at,in,on分别在什么时候用（分别表时间的地点

问几个英语语法的问题
1.什么时候动词的进行式要双写末字母加ing?
2.at,in,on分别在什么时候用（分别表时间的地点时）
3.to和for分别用在什么时候
望达人赐教
at,on请说一下用于地点的时候的用法
请举一下介词跟look的搭配
to china如果是靠近中国，那walk to china是不是走近中国呢？

现在进行时是由助动词to be 的现在时 + 现在分词构成：
肯定式 否定式 疑问式
I am working.You are working.He (she) is working.We (you,they) are working. I am not working.You are not working.He (she) is not working.We (you,they) are not working. Am I working?Are you working?Is he (she) working?Are we (you,they) working?
现在分词的构成,是在动词原形上加—ing, 但是应该注意：
情况 变化 例词
动词以单个e 结尾 去掉e, 加 ing Love _lovingArgue _ arguing
动词以 —ee结尾 直接加 ing Agree_ agreeingSee _ seeing
动词为单音节：以单一元音字母 + 单一辅音字母结尾 辅音字母双写,再加 ing Hit _ hittingRun _runningStop _ stopping
动词为双音节或者多音节：最后一个音节为重读音节,以单一元音字母 + 单一辅音字母结尾 辅音字母双写,再加 ing Be’gin be’ginningAd’mit ad’mitting
以 y 结尾的动词 直接加 ing Carry carryingEnjoy enjoying
现在进行时的功用
1） 表示说话时正在发生或者进行的动作
Please don’t make so much noise, I’m studying.
Let’s get out. It isn’t raining any more.
2) 表示在现在相对较长一段时间内正在进行的动作,但是说话一刻不一定在做的动作
Have you heard about Tom? He is building his own house.
David is teaching English and learning Chinese in Beijing.
这些动作,在说话时并不一定在发生或进行,而是在包括说话的一刹那在内的一段时间内发生、进行的.
3）表示最近的确定的安排
Ann is coming tomorrow.
Oh, is she? What time is she arriving?
At 10:15.
Are you meeting her at the station?
I can’t. I’m working tomorrow morning.
以上句子也可以用be going to (do) 的形式来表示.但是谈论已确定的安排时候,用现在进行时态显得更加自然,除非受到动词的功能的限制.在此,切不可用will, 如：
Alex is getting married next month. 不能用 will get married.
4) 和always 连用表示某种情绪,可能是厌烦也可能是赞扬,如：
Tom is always going away for weekends.
My husband is always doing homework.
有些动词是表示一种状态而不是动作,一般不用于进行时.例如,我们一般不说 I am knowing, 而说 I know. 常见的这类动词有：
want like hate know see hear believe understand seem
think(相信) suppose remember need love realize mean forget prefer have （拥有）belong
To understand is to accept. 理解就是接受
Do you like Beijing?
Do you see the rainbow?
I remember him very well.
I think I understand what he wants.
一般现在时和现在进行时的比较
一般现在时表示的是一般、重复的动作或者事情
现在进行时表示说话时或说话前后正在发生的动作或事情,如：
Tom plays tennis every Sunday.
Where’s Tom? -------He is playing tennis.
What do you do? 你是干什么工作的?
What are you doing here? 你在这里干什么?
一般现在时是表示经久的情况,而现在进行时表示的是暂时的,如：
My parents live in Shanghai. They have been there for 50 years.
She’s living with some friends until she can find an apartment.
参考资料：http://zhidao.baidu.com/question/18009080.html?si=4
⑴ 时间或地点介词in、on、at的用法区别：表示时间时, in表示在一段时间里(在将来时句子中则表示在一段时间之后), on表示在具体的某一天或者某天的上下午等, at表示在某个时刻或者瞬间；表示地点时, in表示在某个范围之内, on表示在某个平面上或与一个面相接触,at则表示在某个具体的场所或地点.如：He was born on the morning of May 10th.(他出生于五月十日的早晨)/ I usually get up at 7：00 in the morning.(我通常在早上的七点钟起床) / His glasses are right on his nose.(他的眼镜就架在他的鼻子上)/ He is at the cinema at the moment.(此刻他正在电影院)
⑵ after与in表示时间的用法区别：“after+(具体时刻/从句)”表示“在…时刻之后”常用于一般时态；“in+(一段时间)”表示“在(多久) 之后”,常用于将来时态.如：He said that he would be here after 6：00.(他说他六点钟之后会来这儿)/ My father is coming back from England in about a month.(我父亲大约一个月以后从英国回来)
⑶ since与for表示时间的用法区别：“since+(具体时刻/that-从句)”表示“自从…起一直到现在”,“for +(一段斶间)”表示“总共有…之久”,都常用于完成时态；如：Uncle Li has worked in this factory since 1970.(李叔叔自从1970年起就在这家工厂工作了)/ Uncle Li has worked in this factory for over 30 years. (李叔叔在这家工厂已经工作了30多年)
⑷ by、in与with表示方式的用法区别：都可以表示“工具、手段”,但是by主要表示“乘坐”某个交通工具或“以……方式”,在被动句中可以表示动作的执行者；in表示“使用”某种语言/文字,with表示“使用”某个具体的工具、手段.如：We see with our eyes and walk with our feet.(我们用眼睛看东西,用双脚走路)/ Please write that article(文章) in English.(请你用英语写那篇文章)/ Let’s go to the zoo by taxi.(我们打的去动物园吧.)/ It was written by Lao She.(那是老舍写的)
⑸ about与on的用法区别：都可以表示“有关…”,但是about的意义比较广,而on主要表示“有关…(专题/课程)”.如：Tom is going to give a talk on the history of America.(汤姆要作一个美国历史的报告)/ They are very excited talking about the coming field trip.(他们兴致勃勃地谈论着即将来到的野外旅游)
⑹ through与across、over的用法区别： through指“穿过…(门洞/人群/树林)”； across和over可以指“跨越…(街道/河流)”,可互换,但是表示“翻过…”时只能用over. 如：Just then a rat (鼠)ran across the road.(就在那时一只老鼠跑过路面)/ There is a bridge across/over the river.(河上有座桥)/ They climbed over the mountain and arrived there ahead of time.(他们翻过大山提前到达了那里)/ The visitors went through a big gate into another park.(参观者们穿过一个大门来到另一个公园)
(7)as与like的区别：两个词都表示“像……”,但是as译为“作为……”,表示的是职业、职务、作用等事实,而like译为“像……一样”,表示外表,不是事实.如：Let me speak to you as a father.(我以父亲的身份和你讲话.)(说话者是听者的父亲) / Let me speak to you like a father.(让我像一位父亲一样和你讲话)(说话者不是听者的父亲)
(8)at the end of、by the end of、to the end、in the end的用法区别：at the end of…既可以表示时间也可以表示地点,译为“在…末；在…尽头”,常与过去时连用；by the end of…只能表示时间,译为“在…前；到…为止”,常用于过去完成时； in the end与at last基本等义,表示“终于、最后”,通常用于过去时；to the end译为“到…的终点为止”,前面往往有表示运动或连续性的动词.如：By the end of last term we had learned 16 units of Book III.(到上学期期末我们已经学习了第三册16个单元)/ At the end of the road you can find a big white house with brown windows.(在路的尽头你能找到一幢有棕色窗户的白房子)/ They left for Beijing at the end of last week.(上周末他们动身去了北京)/ In the end he succeeded in the final exams.(他最终在期末考试中考及格了)/ We should go on with the work to the end.(我们应该把工作干到底)/ Follow this road to the end and you will see a post office.(沿这条路走到底就能看见一家邮电局)
(9)for a moment、for the moment、in a moment、at the moment的区别：for a moment“一会儿、片刻”(=for a while),常与持续性动词连用；for the moment“暂时、目前”,常用于现在时；in a moment“一会儿、立即、马上”(=soon; in a few minutes),一般用于将来时；at the moment“此刻,眼下”(=now),用于现在进行时.如：Please wait for a moment.(请稍等)/ Let’s leave things as they are for the moment.(暂时就维持现状吧!) / I’ll come back in a moment.(我过会儿回来)/ I am very busy at the moment.(眼下我很忙)
(10)but的问题：用介词but引出另一个动词时,要注意：如果前面有do,后面就用原形动词,前面没有do时,后面的动词要加to.如：I could do nothing but wait.(我什么也做不了只能等) / They had no choice(选择) but to fight.(他们没有选择只有战斗)
(11)in front of 与in the front of： in front of“在…的前面”, 与in the front of“在…的前部”.如：A car was parking in front of the hall.(大厅跟前停着一辆汽车)/ In the front of the hall stood a big desk.(大厅前部立着一个大讲台)
(12)except (for)与besides的区别：except“除了”,表示排除掉某人物,即不包含；而besides“除了”则表示包含,即“不仅……又……”.如：Everyone went to the Palace Museum except Tom.(除了Tom,大家都去了故宫博物院)(Tom没有去故宫)/ Besides Chinese he also studied many other subjects.(除了汉语之外,他还学其他许多功课)(“汉语”也是他学的功课之一)
other than 除了.之外. There 're nobody here other than me 与.不同. 与.不同方式.we can't get there other than by swimming.
Apart from : with the exception of ...; besides... Apart form a few scratches, the car was undamaged.