Problem: How does the sentence end?

The woman tried use the new medication to ease her period but the 
Answer: period was too strong.

Problem: How does the sentence end?

Adam wrote a thorough analysis of the book read in class, but Neil wrote a superficial  one, because 
Answer: Neil was lazy.

Problem: How does the sentence end?

The lemmings fled from the hill and into the field, as the 
Answer: hill was devoid of fun activities for them.

Problem: How does the sentence end?

Most customs around the world do not tolerate obvious mistakes people make. The 
Answer:
Mistakes are costly.