It was during the Ming Dynasty________the Great Wall was repaired and extended to take on the appearance it has today.

Was it through Mary, _____ was working at a high school, ____ you got to know Tom?

We have some bread, but we have ________ milk. Let’sbuy some milk.

It’s important _______ us students to make a plan _______ our studies before a new term starts.

Mr. Wu came into the classroom , abook in his hand.