What’s wrong with you, sir? — My flight ______ ten minutes ago. What should I do?

I drove to Zhuhai for the air show last week.— Is that ____________ you had a few days off?

This is ____book I borrowed yesterday. Isn’t it ____interesting one?

We prefer the songs that_______ great lyrics.

Though they are______little children , they have worked out _______many difficult math problems.