英文簡單文法問題

I have bought a car ( 用現在式=你所表達的未超出那時間範圍. )
可以說: *today. *this month. (7月) *this year ( 2015 )

I bought a car ( 用過去式=你所表達的已超出那時間範圍. )
*yesterday. *last month. *last year.
*什至可以說 : this morning. ( 如你在下午對人說 )

I had bought a car ( 未完意)
* when you was a baby. ( 必須修飾) * in 1997.

用past tense 或 past perfect tense 是取決你補充//說明,

The simple past:-I bought a car yesterday.--Began&completed in the past w/o any connection with the present.
Past Perfect:-Before1997 arrived,I had bought the car.----When 2 actions happened in past one after another, we use past perfect for 1st action.
Here action:-Re: after=Before1997!

我是想問past tense 跟 past perfect tense...

請先等等！！！

你是否想問 PRESENT perfect tense 和 past tense 的比較？
不是 PAST perfect tense 和 past tense 吧？

請看：
https://www.ego4u.com/en/cram-up/grammar/simpas-preper

2015-07-01 04:18:13 補充：
可是你句子 "I have bought a car." 是 present perfect tense 啊！