One third of our school _________ covered by trees, while the majority of our students ________ girls. 

In my pencilbox, ______ a pen, two pencils and three rulers.

 — A number of people _______ killed by the terrorists at the Urumqi train station.— _______ terrible it is!

Her brother, Jim Green,  ________ America.

There are usually 28        in a person’s mouth, so we should listen to the doctor’s ______ to protect（保护）them.