trained for和trained in的区别
trained for更强调for a particular purpose
如：Soldiers are trained for war./a dog trained for coursing
如：a scientist trained in physics/a person trained in pharmacy
举个例子，trained 和having been trained区别是什么？OJZ
No one can walk the wire without a bit of fear unless he was trained when he was very young.
句子中包含两个状语，一个是条件状语 一个是时间状语，当主从句主语一致 ，并且从句当中含有be 动词的时候，就可以将从句中的主语和be 动词省略掉。
而 having been done是现在完成进行时态，是完成时态的一种，它是指动作从过去某一时间开始一直持续到现在，并且有可能继续进行下去，现在或者当前正在进行着，是与现在有关的。
如：She has been skating for three hours. 她已经滑了三个小时。(现在还在滑。）
be trained for是什么意思
6000 volunteers will be trained for the Olympic and Paralympic games in Athens in 2004.
should animals be trained to help humans 以这个题目写篇作文咯
I think animals should be trained to help humans.
There are many people who are alone and lonly in the world. I think they will be very happy if there is a dog who can help them in their daily life. Many people who are blind and deaf usually have a difficult life. If the dog can be trained to know some of the simple instructions,such as opening the door, carring the books ect, then those people won't suffer a lot from the life. I once read many stories about the leading dog that help people in the foreign countries. I just think it is necessary to train animals to help people, especially the dogs. I think the dogs are the kindest animals in the world. They can not only protect you but also give you much help if they are well trained.
Though some people think it will be cruel to train animals and we should respect the rights of animals. I still believe animals should be trained to help people. And I also believe animals will be happy too if they can do as much as they can to help humans.