第三人称单数是什么规律?助动词呢?

1.He/She is a student .
1.He/She was a student .
2.He/She has a good habit .
2.He/She had a good habit .
3.He/She does well in reading .
3.He/She did good that night .
4.He/She works hard .
4.He/She worked hard .
再问： 人名所有格呢？