Problem: How does the sentence end?

Joel walks up the driveway slower than Leslie does although 
Answer: Leslie is an older person.

Problem: How does the sentence end?

The man found less clams at the beach than oysters, because the 
Answer: oysters were abundant.

Problem: How does the sentence end?

Nate was unexpectedly early to his appointment today. So while waiting he compared the time on his watch to the wall clock and concluded the 
Answer: watch must be running fast.

Problem: How does the sentence end?

Derrick was much more alert than Lawrence, so 
Answer:
Derrick didn't have to worry about falling asleep while driving.