He tried his best to solve the problem, _______ difficult it was.

How long have you ________ your penfriend—For five days. I received it last Sunday.

I didn’t like Aunt Lucy, who＿＿without warning and bringing us presents

25．How convenient the public transportation is! There ______ be any difficulty traveling around．

If he , he that food.—Luckily he was sent to the hospital immediately