A piece of evidence
  Exposure of the body to strong sunlight maybe harmful.
  A good command of English is greatly due to much exposure to that language.
  point to
  point at
  point out
  I will have finished the whole book by the end of this term.
  We got up early to arrive at the school on time.
  I came in the room only to find no body there.
   
   
  被动语态：句子的主语是谓语动作的接受者。
  例句：
  1.         Lei Feng is respected by us all.
  2.         The glass was broken yesterday.
  3.         I’ve been given some advice.
  4.         Tom will be sent to college.
  5.         The work had been finished by then.
  6.         I was told that he would be given some money.
  主动语态：句子的主语是谓语动作的发出者。
  例句：
  1.         He goes to school by bus.
  2.         Li Hong is doing her homework now.
  3.         She’s giving me some advice.
  4.         My mother took me to a hospital.
  5.         They’ll come back soon.
  6.         By the end of last term we had learned 500 words.
  7.         He said he would come here the next week.
  被动语态常用的时态有：
  1.         一般现在时：Garage-sale items usually are priced at a very small part of their original cost.
  2.         一般将来时：The young driver will be stopped by the policeman if he drives that way.
  3.         一般过去时：Not a word was heard from him since he left home.
  4.         现在完成时：This dish has been prepared by the chief cook.
  5.         将来完成时：The whole book will have been finished by the end of this term.
  6.         过去完成时：He told me that the tree in front of our building had been stricken by lightning.
  7.         现在进行时：This novel is being retranslated.
  8.         过去进行时：A new stadium was being built when we got there last year.
  被动语态没有将来进行时和三种完成进行时，因为be, being, been这三个词任何两个都不能同时使用。
  特殊的被动语态结构：
  l         情态动词+do→情态动词+be done
  Eg:
  1.         The work must be finished today.
  2.         She should be praised for her work.
  3.         Everything that can be done must be done.
  l                                           Have to do→have to be done
  Eg:
  1.         Mary’s mother had to be operated on.
  2.         The meeting has to be put off.
  l                                           Use to→used to be done
  Eg: The plan used to be forgotten.
    Be going to = be going to be done
  1.         The plan is going to be carried out.
  2.         The project is going to be completed next month.
  l 要求双宾语的动词的间接宾语常作被动结构中的主语，而直接宾语作保留宾语；当直接宾语作主语时，原间接宾语作为保留宾语常放在介词to之后（但make, buy的要使用for）。
  Eg:
  1.         We are offered a good job.
  2.         A good job is offered to us.
  3.         Lots of money was given to him.
  4.         A library with 5000 books is offered to the nation as a gift.
  5.         A new book was bought for me.
  6.         A pair of shoes was made for him.