Problem: How does the sentence end?

It was difficult for Carrie to control anger at bad drivers but Laura found it easy. 
Answer: Laura had always had a calm demeanor.

Problem: How does the sentence end?

The math test made Mike tired, while he did not really mind the history exam. The 
Answer: history exam was much shorter in length.

Problem: How does the sentence end?

Aaron got a new pet dog for his birthday but not Neil because 
Answer: Aaron really likes animals.

Problem: How does the sentence end?

Ursula only bought the parchment paper on sale instead of the plain paper, because the 
Answer:
parchment paper was usually more expensive.