Over time computers have been changed quite a

Over time computers have been changed quite a lot. The first computer in the world huge Modern computer smaller

Nowadays, computers have been used in many aspects. Can you figure out some possible usage of computers in modern society? Answers: 1. Computers have been used in offices and homes since the 1970 s. 2. Computers have also been put into robots and used to make mobile phones as well as help with medical operations. 3. Computers have been put into space rockets and sent to explore the Moon and Mars.

Thinking: Do they have anything in common? 1. Over time computers have been changed quite a lot. 2. Computers have been used in offices and homes since the 1970 s. 3. Computers have also been put into robots and used to make mobile phones as well as help with medical operations. 4. Computers have been put into space rockets and sent to explore the Moon and Mars. Sentence structure: subject + have/has been done The Present Perfect Passive Voice

Sentence structure: subject + have/has been done Meaning： Something has been done by someone at sometime up to now. 现在完成时被动语态表示到现在为止已经完成的或发生 在过去，但对现在仍有影响的某个被动的动作，其主语 为动作的承受者， 意为“…已经被…”。 E. g. This supermarket has been built since two years ago. action doer