Problem: How does the sentence end?

Donald came over to Kyle's garden and showed him the proper way to harvest garlic.  
Answer: Donald was generous.

Problem: How does the sentence end?

Cynthia was more experienced in using a phone app than Kayla because 
Answer: Cynthia had grown up with cell phones.

Problem: How does the sentence end?

Angela loved studying English but Amy preferred math. it was difficult for 
Answer: Amy to write a story.

Problem: How does the sentence end?

The biting wind froze the pipe but not the chimney, as the 
Answer:
pipe was insufficiently insulated.