Problem: How does the sentence end?

Joel preferred to drive when Christopher was in the car, since
Answer: Joel was a very steady driver.

Problem: How does the sentence end?

I used vinegar on a carpet stain today, but now my room smells terrible since the
Answer: carpet is too thin.

Problem: How does the sentence end?

I decided to give my girlfriend a card instead of the candy as the
Answer: card is more intimate.

Problem: How does the sentence end?

Samantha sometimes reads things backwards and has trouble with things, while Lindsey does not, so
Answer:
Lindsey is probably normal.