The correct verb form is "bought," as the sentence is in the past tense,
indicated by the phrase "last week." "Bought" is the past tense of "buy."
"Buy" is the base form of the verb.
"Buying" is the present participle/gerund form.
"Buys" is the third-person singular present tense form.
"let me tell you it will not"
"میں آپ کو بتاتا ہوں کہ ایسا نہیں ہوگا"
"Will" accurately conveys a strong certainty that light will not come.
The sentence "I shall be working till late at night" is in the Future Continuous tense.
It describes an action that will be happening at a specific time in the future.
The sentence "Ali had been walking three miles a day before she broke her leg" is in the past perfect continuous tense.
It showing an action (walking) that was ongoing before another past event (breaking her leg).
Past Indefinite tense
Active Voice= Subject + Second Form of Verb + Object.
Passive Voice = Object + was/were + third of verb + by + subject.
By the time he was thirty, he had won many tournaments."
جب وہ تیس سال کا تھا، اس نے بہت سے ٹورنامنٹ جیت لیے تھے۔"
***
"had won" is used in this sentence to convey the past perfect tense.
This sentence, "By the time he was thirty" establishes a point in the past.
The action of winning tournaments ("had won") is placed before this past point in time
past continuous + when + past tense formula
The formula is Subject + was/were + (verb + -ing) + object + other words
"I was walking down the street when it began to rain"
ND22-7-2023
Having elected him president, the people gave him their loyal support.
having elected gave past participle
"Having" + past participle means that the person(s) being referred to have done the action of the verb.
ND13-07-2023
Present Perfect Tense into Past Perfect Tense
Helping verbs
Present: Have/Has
Past: Had
Have been & have been are helping verbs of Present Perfect Continuous Tense.