Problem: How does the sentence end?

The razor blade got broken when sharpening the boy's  pencil because the 
Answer: pencil is hard.

Problem: How does the sentence end?

I always use reusable bag rather than plastic bag when I shop because the 
Answer: plastic bag is harmful for the environment.

Problem: How does the sentence end?

Lawrence really disliked brushing his teeth unlike Donald, therefore 
Answer: Donald had wonderful breath all of the time.

Problem: How does the sentence end?

Oranges will cause diabetes, but not carrots, since the 
Answer:
oranges contribute to aggravating the disease.