Problem: How does the sentence end?

When it comes to travel, Eric likes to ride a bicycle, but William uses a car. This is due to 
Answer: William being environmentally ignorant.

Problem: How does the sentence end?

Emily found standup comedy difficult but it came naturally to Victoria. 
Answer: Victoria had always had a thick skin for hecklers.

Problem: How does the sentence end?

Angela was filling out a report for Elena for 
Answer: Elena forgot how to put all the facts and figures in a easily digestable format.

Problem: How does the sentence end?

Christopher wasn't a plumber but he knew Matthew was so 
Answer:
Christopher called him to fix his sink.