英语语法问题比较低级的Yesterday,the firemen examined the ground.和Yester

1.
Yesterday,the firemen examined the ground.和Yesterday,the firemen have examined the ground.有什么区别?
Yesterday,the firemen examined the ground.

一般过去时态,用于说话以前发生过的事情,动作.句子中有明确的,具体的过去时间.

句子中有明确具体的过去时间,句子谓语动词,不用现在完成时态.现在完成时间态用于描述过去发生过的,或者开始的动作,关注的是是否发生过,做过；或者关注动作的效果,动作持续的时间,或者影响. 句子中,要么没有过去时间,要么与下面的时间状语：
for +时间段,
since +时间点

句子中,常有just, alreay, never, 等副词
They have already examined the ground.

2.
They were also quite sure that a cigarette end did not start the fire.和
They were also quite sure that a cigarette end were not start the fire.
第二句是错的.were not start the fire ,是错误的, be +do 这个什么结构都不是,不存在这个语言现象.
3.had been 和has been我总是分不清楚该怎么用

had been ,过去完成时态
has been 现在完成时态

过去完成时：发生在过去的过去的事件,用过去完成时态描述.
过去的过去：
He came home late. He had been to the cinema.
一个句子里,说两件过去的事件,发生在先的可以用过去完成时,在后用一般过去时.
He had been to the cinema before he came home.

has been ,现在完成时态,前面有说明.
He has been to school.