教科版小学科学五年级下册《改变物体在水中的沉和浮》ppt课件.ppt

Unit 9 When was it invented?
一、学****目标:
掌握一般现在时、一般过去时和含有情态动词的被动语态的用法。
二、语法介绍:
英语中动词的语态分成两种:主动语态和被动语态。当句子的主语是动作的执行者时,谓语的形式叫主动语态;当句子的主语是动作的承受者时,谓语要用被动语态。
㈠含义:动词的被动语态一般译成“被…”,但是根据汉语表达****惯,有时“被”也可以不译出。
㈡构成:被动语态一般的构成形式为:be+动词过去分词(+by+动作的发出者)。其中助动词be有人称、数和时态的变化。
一般现在时:am/is/are+done(过去分词)
一般过去时:was/were+done(过去分词)
含有情态动词的:情态动词+be+done(过去分词)
㈢方法:
1、将主动语态句中的宾语变为被动语态句中的主语,主动语态句中的主语变为被动语态句中介词by的宾语。
2、将主动语态句中谓语动词变成:助动词be+该动词的过去分词,但时态不改变。
3、助动词be要与新的主语保持单、复数一致;若主语和宾语是人称代词时,“格”应作相应的变化。
口诀:宾变主,主变宾,谓变be done时不变,数格必须随着变。
The workers make machines in this factory.
Machines are made by the workers in this factory.
注意:不及物动词没有被动语态。
㈣例句:
people speak English in China.
English is spoken by many people in China.
invented the telephone in 1876.
The telephone was invented by Bell in 1876.
must look afer the old man.
The old man must be looked after (by us).
㈤特殊情况:
⑴(含有双宾语的句子变被动语态)
剖析:含双宾语的主动语态的句子变为被动语态时,常把那个指人的间接宾语变为被动语态的主语;也可把那个指物的直接宾语用作主语,但此时必须在间接宾语前加上介词to或for。如:
He gave me a book.
→I was given a book by him.
→A book was given to me by him.
口诀:如遇双宾语,一般变间宾。若把直宾变,to,for间宾连。
⑵感官动词和使役动词在主动句中其后的动词不定式不带to,但变被动句时必须加上to。如:
The boss made her work for 16 hours a day.
→She was made to work for 16 hours a day.
口诀:感/使动词真叫怪,to来to去记心怀,主动语态to离去,被动语态to回来。
三、对应练****br/>㈠选择填空
1. The children ____ by the nurse.
A. were looked      B. looked after
C. were looked after D. looked
lab ____ about five years ago.
A. was builded B. was built C. builds D. has been built
glass ______ . It _____ by little Tom this morning.
A. broke, is broken  B. is broken, was broken
C. was broken, broke D. has been broken, broken
______the way to the railway station by a policeman.
A. was shown B. showed C. have shown D. was showing
When water__
____ , it will be changed into vapour.
A. is heated B. heating C. has heated D. heats
can't enter the room because its door______ .
A. locked B. locks C. is locked D. is locking
______day and n