Problem: How does the sentence end?

We returned the drill and opted to purchase a hammer, since the 
Answer: hammer was conducive to our building project.

Problem: How does the sentence end?

The plank James intended to break the limestone with keeps breaking because the 
Answer: limestone is harder.

Problem: How does the sentence end?

At the high school, Rebecca is better at talking to girls than Laura because 
Answer: Rebecca is smoother.

Problem: How does the sentence end?

We left the boat in the dock and took the barge instead, as the 
Answer:
barge had a easy time on the wavy ocean.