Past Simple : (1) This tense denotes an action completed in the past as in : in 1980, in May, on Monday, at 10 a.m etc. We can mention the exact time when the action took place .

• He went to Delhi yesterday.
• They ate up all the mangoes we had kept in the basket.
• When did you see him last?
• Did he lose his key?  Yes he did.( whether he got back the key now or not is not mentioned/clear here)
• What did you say when he came to quarrel with you?
• I didn’t have any money with me to help you.
• He completed the work single-handed before schedule.

(2)  We use past tense (Not present perfect) if there is no connection with the present( for example , things that happened a long time ago)

• Chinese invented printing. (Not  ‘have invented ‘)
• How many plays did Shakespeare write? ( Not ‘ has Shakespeare written’)
• He is a historian.  He has written many books on his subject. ( He still writes books, he is still alive.  In this context, we use ‘ present perfect ‘ instead of past.)