have been 同 had been 有乜唔同? thx 各位

have/has + past participle (e.g. eaten) = present perfect tense
had been + past participle = past perfect tense

present perfect tense 有以下2種用法:

1) past action with no time specified (已完成的動作,但冇講明幾時做)
e.g. I have done my homework.

2) action from past to present
e.g. I have studied for five years. (直到目前為止,我已讀了五年)

past perfect tense
絕大部分情況下都有2個past action; 做先果個用past perfect tense, 做後果個用simple past tense.
e.g. The robber had escaped when the police arrived. (警察到時個賊已逃走左)

另一個用法就係reported speech, if the original statement is in the present perfect tense
e.g. He said, "I have finished my work." (Direct speech)
He said that he had finished his work. (Indirect speech)

had 系 過去曾經
have 系 現在已經

i've had been to san francisco
i have been elected as the president of the organization