what is the difference between Has and Had?
'Have, has, had' - used to make perfect tense; third person plural and 'I', 'you', 'we' come with 'have'; third person singular uses 'has'; 'had' is used with all person and number in the past tense. For example:
I have done my homework.
She has done her homework.
They had done their homework.
I have done my homework.
She has done her homework.
They had done their homework.