（4）表示过去连续发生的动作时，要用过去时。这种情况下，往往没有表示过去的时间状语，而通过上下文来表示。
The boy opened his eyes for a moment，looked at the captain，and then died.
那男孩把眼睛张开了一会儿，看看船长，然后就去世了。

（5）表示过去一段时间内经常或反复的动作。常与always，never等连用。
Mrs. Peter always carried an umbrella.彼得太太过去老是带着一把伞。
（只是说明她过去的动作，不表明她现在是否常带着伞。）
比较：
Mrs. Peter always carries an umbrella.彼得太太老是带着伞。
（说明这是她的习惯，表明她现在仍然还习惯总带着一把伞）
Mrs. Peter is always carrying an umbrella.彼得太太 总是带着一把伞。
（表示说话者对这一动作或行为厌烦）
I never drank wine.我以前从不喝酒。
（不涉及到现在，不说明现在是否喝酒）

（6）如果强调已经终止的习惯时要用 used to do（过去常常做，而现在不那样做了）
He used to drink alcohol.他过去喝酒。
（意味着他现在不喝酒了。喝酒这个动作终止了）
I used to take a walk in the morning.我过去是在早晨散步。
（意味着现在不在早晨散步了）
比较：
I took a walk in the morning.我曾经在早晨散过步。
（只是说明过去这一动作）

（7）有些句子，虽然没有表示过去确定时间的状语，但实际上是指过去发生的动作或存在的状态的话，也要用过去时。
I didn''t know you were in Paris.我不知道你在巴黎。
（因为在说话时，我已经知道你在巴黎了。这句话指的是说话之前，所以只能用过去时表示。实际上，这句话暗指：But now I know you are here.）
I thought you were ill.我以为你病了呢。
（这句话应是在说话之前，我以为你病了。但是现在我知道你没病）

一般过去时三变技巧:
一变：肯定句变为否定句
技巧1.当句中含有情态动词或助动词could，would，should等时，可直接在其后面加not构成否定句。例如：
I could get you a concert ticket. → I could not / couldn't get you a concert ticket.
技巧2.当句中含有系动词was，were 时，可直接在其后加not构成否定句。例如：
I was on the Internet when you called me. → I was not / wasn't on the Internet when you called me.
技巧3.当句中谓语是除情态动词、助动词、系动词was, were以外的动词时，在该动词之前加did not / didn't，动词还原，构成否定句。例如：
The famous singer sang some Chinese songs. → The famous singer did not / didn't sing any Chinese songs.

二变：陈述句变为一般疑问句
技巧1.移动词语的位置。将was，were, could，would，should等移到句首。例如：
He could pack his things himself. → Could he pack his things himself?
技巧2.添加助动词did。谓语是除情态动词、助动词、系动词was, were以外的动词时，在主语之前加did，动词还原。例如：
Mr Li looked very old. → Did Mr Li look very old?

三变：陈述句变为特殊疑问句
技巧1.确定疑问词：人who / whom，物what，地点where，时间when / what time，原因why，频率how often，长度how long，距离how far等等。例如：
They gave the concert last night. → When did they give the concert?
技巧2.辨认结构形式：疑问词+情态动词/助动词/ was / were / did +主语+...? 例如：
The accident happened near the station. → Where did the accident happen?

考点名称：被动语态

• 语态：
  是动词的一种形式，它表示主语和谓语的关系。
  语态有两种：主动语态和被动语态。
  如果主语是动作的执行者，或者是说动作是由主语完成的，要用主动语态；
  如果主语是动作的承受者，或者是说动作不是由主语而是由其他人完成的，则用被动语态。

• 被动语态的构成:
  被动语态的基本结构：
  主语+be +过去分词(+by+动作的发出者）
  ① 一般现在时：am/is/are+过去分词
  如：Trees are planted every year.
  ② 现在进行时 am/is/are+ being +过去分词
  如：The road is being repaired. 
  ③ 现在完成时 have/has + been +过去分词
  如：The work has been finished.
  ④ 一般过去时 was/were + 过去分词
  如：The story was told by him.
  Many birds were killed last year.
  ⑤过去进行时 was/were+ being + 过去分词
  如： The new house was being painted when I got home.
  ⑥过去完成时 had +been+ 过去分词
  如： He told me that the work had been finished.
  ⑦一般将来时  will +be + 过去分词
  如：The problem will be discussed tomorrow.
  ⑧ 过去将来时 would/should +be +过去分词
  如： He said that the Christmas tree would be put up soon.
  ⑨情态动词的被动语态
  情态动词+ be +过去分词    
  如：The problem must be solved soon.
  Children should be taught to love animals.

• 被动语态使用注意:
  1. 不及物动词无被动语态。 如：happen, break down, come out......
  What will happen in 100 years.
  The dinosaurs disappeared about 65 million years ago.
  2. 有些动词用主动形式表示被动意义。 如： write, sell, ride.....
  This pen writes well.
  This new book sells well.
  3. 感官动词或使役动词使用省略to的动词不定式，主动语态中不带“to”，但变为被动语态时，须加上“to”。
  例：make somebody do something→somebody+ be +made to do something
  see somebody do something→somebody +be +seen to do something
  A girl saw my wallet drop when she passed by.→My wallet was seen to drop by a girl when she passed by.
  The boss made the little boy do heavy work.→The little boy was made to do heavy work by the boss.
  4. 如果是接双宾语的动词改为被动语态时，直接宾语（物）作主语，那么动词后要用介词，这个介词是由与其搭配的动词决定。
  He gave me a book.→A book was given to me by him.
  He showed me a ticket.→A ticket was shown to me by him.
  My father bought me a new bike. →A new bike was bought for me by my father.
  5. 一些动词短语用于被动语态时，动词短语应当看作一个整体，而不能丢掉其中的介词或副词。
  We can’t laugh at him. →He can’t be laughed at by us.
  He listens to the radio every day. →The radio is listened to by him every day.
  The nurse is taking care of the sick man. →The sick man is being taken care of by the nurse.
  构成be+done.

• 主动句变为被动句所遵循的4个步骤：
  ①把原主动句中的宾语变为被动句的主语
  ②把动词变为被动形式即be +过去分词，并注意其人称和数随主语的变化，而动词的时态则保持不变。
  ③原主动句的主语如需要则放在by后面以它的宾格形式出现（注代词的宾格），如不需要则可省略。
  ④其它的成分（定语、状语）不变。
  
  不用于被动语态的情形：
  ①不及物动词没有被动语态
  这类动词有take place, happen, come about, break out, appear, disappear, last,  arise等。
  例如：A fire broke out during the night.
  ②某些静态动词不用于被动语态
  这类动词有have, lack, fit, hold, suit, resemble等。 
  例如：My shoes do not fit me.
  ③宾语为相互代词和反身代词时不用于被动语态
  例如：We should help each other.
  
  关于主动形式表示被动意义:
  ①系动词（如look, sound, smell, feel, taste, prove等）要用主动表被动，因为系动词为不及物动词，它们没有被动语态形式。
  例如：The building looks very beautiful.
  ②当open, close, shut, lock, move, read, wash, clean, cook, cut, wear, carry 等用作不及物动词且表示主语的某种属性时，通常用主动形式表示被动意义。
  例如：The book sells well.
  ③有的动词本身含有被动意味，通常用主动形式来表示被动含义。
  例如：Her eyes filled with tears.
  ④不定式to blame, to let用作表语时，通常要用主动表被动。
  例如：Who is to blame?
  ⑤某些“be+形容词+to do”结构中的不定式通常要用主动形式表示被动意义。
  例如：The book is difficult to understand.
  ⑥不定式用于某些动词（如have, have got, get, want, need等）的宾语后作定语时，如果不定式的逻辑主语就是句子的主语，通常用主动形式表示被动意义。
  例如：Do you have time to help us?
  ⑦在too...to do sth.和...enough to do sth. 这两个结构中，若主语与其后不定式为to do sth.被动关系，则该不定式通常用主动形式表示被动意义（有时也可直接用 被动式）。
  例如：The writing is too faint to read.
  ⑧be worth后的动名词要用主动表被动。
  例如：This movie is worth seeing.
  ⑨在need, want, require等少数表示“需要”的动词后的动名词用主动形式表示被动意义。
  例如：The house needs cleaning.