Explanation

There were a few people in the mall, so we weren’t completely alone.

“A few” is used for a small number of countable nouns like “people”.

Explanation

Today's weather is worse than yesterday's."

When comparing two things (today's weather vs. yesterday's), you use the comparative form of adjectives.

The comparative form of "bad" is "worse".

"Bore" is unrelated and refers to boredom, not weather.

"Bad" is the base form and not suitable in a comparative sentence.

Explanation

She wished she had bought the new car.

اس کی خواہش تھی کہ اس نے نئی کار خریدی ہو۔

"She wished" refers to a past regret, so the past perfect "had bought" is correct.

Explanation

"Karachi isn't as populated as it was 10 years ago."

The sentence needs a word that indicates a comparison between the current population of Karachi and its population 10 years ago.

"As" is the correct word to express this comparison. 

Explanation

"I wasn't feeling well, so I decided not to go to university."

"So" is used to show cause and effect in a simple, natural way. 

"So" fits the informal tone of the sentence and is the most natural choice.