三、现在完成时(have/has done, have/has been done)
1.现在完成时常用的时间状语有lately，recently，just，already，yet，up to now，till now，so far，to this day，in the past few years/months/weeks/days，over the past few years，during the last three months，for the last few centuries，through centuries，throughout history等。
2.在时间状语从句中，谓语动词可以用现在完成时代替将来完成时。例如：
Mother won’t let her watch TV until she has finished her homework.母亲要到她做完作业才让她看电视。
The dinner party will begin after all the guests arrive/have arrived.所有的客人到了以后，聚餐就开始了。
3.has/have been to与has/have gone to的区别。has/have been to表示“曾去过”，说明有某种经历；has/have gone to表示“已去某地(在途中或已经到达目的地)。例如：
They have been to Sweden many times.他们去过瑞典许多次了。
Jack isn’t in. He has gone to the supermarket.杰克不在，他去超市了。
4.现在完成时特别强调瞬间动词和持续性动词。瞬间动词表示短暂、不能持续一段时间的动作，如come，go，leave，start，begin，become，receive，die，而持续性动词表示能持续一段时间的动作，如work，stay，live，learn等。下面列举一些常用的瞬间动词和对应的持续性动词：leave，be away；die，be dead；put on，wear；fall ill，be ill；borrow，keep；catch cold，have a cold；buy，have；join the army，be in the army。例如：
My brother has been in the army for some time.我兄弟参军有一段时间了。
My brother joined the army some time ago.我兄弟是一段时间以前参的军。
He has been up for an hour.他起床有一小时了。
He got up an hour ago.他一小时前起的床。
Jack has been a soldier for some time.杰克当兵有段时间了。
Jack became a soldier some time ago.杰克是在一段时间前当的兵。
但是，瞬间动词的肯定结构可以用不与“for+时间段”连用的现在完成时，说明某个动作已经发生；瞬间动词的否定结构可以与“for+时间段”连用，说明某动作不发生的状态可以持续一段时间。例如：
Hurry up! The film has begun.快一点！电影已经开始了。
We haven’t heard from her for a long time.我们很久没收到她的来信了。
5.句型It is/has been + 时间段 + since(从句的谓语动词用一般过去时) 例如：
It is two months since they came here.他们来这里两个月了。
It is ten years since his father died.他父亲去世有十年了。
6.持续性动词用于含有till/until的句子结构，表示该动作一直持续到某时间终止；而瞬间动词的否定结构用于till/until句子中，表示某动作不发生的状态延续到某时间终止，可译为“直到……才……”。例如：
They went on working till supper time.他们继续工作到晚餐时间。
They didn’t stop wording till supper time.他们一直到晚餐时间才停止工作。
I will stay until you come.我会等到你来。
I won’t leave until you come.直到你来了，我才会离开。
7.句型this is the first/ second/ third … time that(从句的谓语动词用现在完成时) 例如：
This is the second time that the products of our company have been shown in the International Exhibition.这是我公司产品第二次参加国际展览会。
四、现在完成进行时(have/has been doing, 一般不用该时态的被动语态)
与现在完成时相比，现在完成进行时更强调，在从过去到现在的时间里，动作或状态一直持续或一直反复出现。例如：
It seems oil has been leaking from this pipe for some time. We'll have to take the machine apart to put it right. 看来，这个管道漏油已有一段时间了，我们将不得不拆卸机器排除故障。
At last you come! I have been waiting for you for the whole morning.你终于来了，整个上午我都在等你。
五、一般过去时(did, was/were done)
1.有些句子中虽然没有表示确定过去时间的状语，但根据上下文的情景可以推断出是过去发生的动作，此时也应用一般过去时。例如：
I didn’t know you were here.我不知道你在这里。(说这句话的时候，我已经知道你在这里了，所以用一般过去时)
I forgot to bring my dictionary with me.我忘记带字典了。(说这句话的时候，我已经想起要带字典)
2.一般过去时用于时间或条件状语从句中，代替过去将来时。例如：
She promised that she wouldn’t tell their mother about it when their mother came back.她答应当他们的妈妈回来时，她不会把这件事告诉她。
He said that he would give her the book if he saw her.他说如果他看到她，他会把这本书给她。
3.一般过去时有时可代替一般现在时，表达一种婉转、客气、礼貌、商量的语气。例如：
I want to ask you if I could borrow your car?我想向您借车用一用，可以吗？
Could you tell me how to get to the nearest post office?您能告诉我去最近的邮局怎么走吗？
六、过去进行时(was/were doing, was/were being done)
1.过去进行时常常用于叙述事件、故事发生的背景。例如：
It was raining heavily. The wind was blowing. A group of soldiers were marching along the highway … 天下着大雨。风猛烈地刮着。一群士兵正沿着公路行军……
2.过去进行时与一般过去时的区别在于，前者强调过去某时刻或阶段动作的进行，不表明动作的完成，后者表示过去某动作已经发生，表明动作已经完成。例如：
They were digging a well last winter. So far they haven’t finished it.他们去年冬天在挖井，至今还未完成。
They dug a well last winter.他们去年冬天挖了口井。
He was designing a project last night. He is going to finish it tonight.昨天晚上他正在设计一个项目，他打算今晚完成。
He designed a project last night. He is going to submit it to the manager today.昨天晚上他设计了一个项目，他打算今天交给经理。
七、过去完成时(had done, had been done)
1.在hardly/scarcely … when，no sooner … than等句型中，主句用过去完成时，从句用一般过去时。例如：
No sooner had I arrived home than the telephone rang.我刚到家，电话铃就响了。(注意主谓倒装)
Hardly had I finished my work when he came to see me.我刚完成工作，他就来看我了。
I had no sooner got into the room than it began to snow.我刚进屋里，天就下雪了。
The very important person had hardly got out of the car when it exploded.这位重要人物刚下车，车子就发上了爆炸。
2.句型It was + 时间段 + since(从句的谓语动词用过去完成时) 例如：
It was two months since they had come here.他们来这里两个月了。
It was ten years since his father had died.他父亲去世有十年了。
3.句型this was the first/ second/ third … time that(从句的谓语动词用过去完成时) 例如：
That was the second that she had seen her grandfather.那是她第二次看见外祖父。
This was the third time that the refrigerator had been repaired.冰箱已经修了三次了。
4.动词hope，expect，think，intend，mean，want，suppose，plan用过去完成时，表示未实现的愿望、打算和意图。例如：
I had intended to see you but I was too busy.我本来打算去看你的，但是我太忙了。
I had planned to buy the premises. The high price forced me into renting it.我本来打算买下这栋房屋，但是其昂贵的价格使得我只能租借。
八、一般将来时(is/am/are going to do, will/shall do, is/am/are going to be done, will/shall be done)
1.同样表示一般将来时，be going to do和will/shall do的区别在于，前者是主观上的打算、意图发生的动作，后者是客观的情况下即将要发生的动作。例如：
Look, the milk is going to boil.瞧，牛奶要开了。(说话者个人的认为)
Look at the clouds. It is going to rain.看那些云，天要下雨了。(说话者个人的认为，如果说It will rain，那是毫无意义的，因为天总是会下雨的)
Look out! The wall is going to fall.当心！这堵墙要倒塌了。
Tomorrow will be Wednesday.明天是星期三。(这是不以说话者个人的意志为转移的)
2.有时候，现在进行时可以用来表示将来，详情请见现在进行时。
3.一般现在时还可以用be to do或者be about to do的结构表示。be to do表示按计划、安排即将发生某事或打算做某事，be about to do强调近期内或马上要做的事。例如：
She is to be seen in the lab on Monday.星期一你准会在实验室见到她。
Don't worry, I am about to make a close examination on you.别担心，我马上就给你做一次仔细的检查。
4.在以if，when，as long as，as soon as，after，before，in case，until，unless等连词以及具有连词作用的副词(immediately，the moment，directly)等引导的状语从句中，一般用现在时代替将来时，强调延续性或动态时，可用完成时。详情请见一般现在时和现在完成时。例如：
I hope his health will have improved by the time you come back next year.我希望到明年你回来的时候，他的身体已经好多了。
九、将来完成时(is going to have done, will have done, 一般不用该时态的被动语态)
1.常用的时间状语一般用by + 将来时间。如：by the end of this year，by 8 o’clock this evening，by March next year以及由by the time…，before或when等引导的副词从句。例如：
By the time you reach the station, the train will have left.等你到车站的时候，火车早就开走了。
The conference will have lasted a full week by the time it ends.会议将持续整整一周。
2.在时间和条件状语从句中，将来完成时则由现在完成时表示。例如：
The children will do their homework the moment they have arrived back from school孩子们放学一回到家，就做作业。
十、语态
1.被动语态的谓语动词可以是及物动词，也可以是不及物动词。当谓语动词是不及物动词时，其后的介词与其形成不可分割的整体，也就是我们所谓的被动语态中的短语动词。在被动语态中，切勿遗漏短语动词的介词。例如：
The sick boy must be attended to immediately.这个生病的男孩必须被立即医治。
The fire had been put out before the fireman arrived.消防队员赶来以前，大火就被扑灭了。
2.有些动词和词组时不可以被用于被动语态的。appear，arrive，become，belong，break out，come true，consist of，die，exist，fail，fall，happen， last， occur， rise， succeed，take place等。
3.有些动词的主动语态表示被动意义，而且常与well，quite，easily，badly等副词连用。blame，cut，lock，read，ride，sell，wash，wear，write等。例如：
The book sells well.这本书很畅销。
This kind of knife cuts well.这种类型的刀很好使。
Who is to blame for the accident?谁应该为这次事故而受到责备？
The car rides smoothly.这车走起来很稳。
