一般现在时则多用来表示一贯的，习惯性的发生的事情
一般过去时讲的是过去发生的事情
WHAT WERE YOU DO THIS MONING?过去时
应该是what were you doing this morning
因为句子里不可以同时有be动词和实义动词，did是助动词，也就是说，是要帮助实义动词的。后面直接动词原型就可以。而were/was后面都要加上动词的现在分词(进行时)或者过去分词(被动语态)。一般现在时表示现阶段发生的动作或状态，以及永恒不变的事实、真理和自然规律，常与时间状语today, every day, on Sunday, every morning等连用。
What day is today ?
We sometimes go to the park on Sunday.
They ride bikes to school every day.
I get up early every morning .
Spring returns in March.
He said spring returns in March..
The sun is bigger than the moon .
一般过去时表示过去阶段发生的动作或状态，常与时间状语yesterday,last year, the day before yesterday , the month before,this morning,five days ago等连用。
What day was yesterday ?
We sometimes went to the park on Sunday last year .
They rode bikes to school the day before yesterday.
I got up early this morning .
I lost my pen five days ago .
http://wenku.baidu.com/view/e24c233183c4bb4cf7ecd1e0.html 一、 一般现在时：
1.概念：经常、反复发生的动作或行为及现在的某种状况。
2.时间状语： always, usually, often, sometimes, every week (day, year, month…), once a week, on Sundays,
3.基本结构：动词 原形 （如主语为第三人称单数，动词上要改为第三人称单数形式）
4.否定形式：am/is/are+not;此时态的谓语动词若为行为动词，则在其前加don't,如主语为第三人称单数，则用doesn't，同时还原行为动词。
5.一般疑问句：把be动词放于句首；用助动词do提问，如主语为第三人称单数，则用does，同时，还原行为动词。
6.例句：. It seldom snows here.
He is always ready to help others.
Action speaks louder than words.
二、 一般过去时：
1.概念：过去某个时间里发生的动作或状态；过去习惯性、经常性的动作、行为。
2.时间状语：ago, yesterday, the day before yesterday, last week,last(year, night, month…), in 1989, just now, at the age of 5, one day, long long ago, once upon a time, etc.
3.基本结构：be动词；行为动词 的过去式
4.否定形式：was/were+not;在行为动词前加didn't，同时还原行为动词。
5.一般疑问句：was或were放于句首；用助动词do的过去式did 提问，同时还原行为动词。
6.例句：She often came to help us in those days.
I didn't know you were so busy