Question

I ______ a new bicycle last week.(bought, have bought, had bought)

Answer 1

Answer:

I bought a new bicycle last week.

Answer 2

I had bought a new bicycle last week.(bought, have bought, had bought)

Explanation:  

‘bought’ is used for simple past tense. ‘bought’ can also be used here but ‘had bought’ is correct because the sentence says that ‘I had bought a new bicycle last week’. The sentence represents the time ‘last week’ so we can choose ‘had bought’.  

‘have bought’ will not come because in present perfect continuous we can write it as “I have been buying” not ‘have bought’