What does “plumber” mean, Alice?—It means a person fixes sinks and toilets.

Are Mr. and Mrs. Wang living alone in the house? —Yes, they have three sons, but ______ of them live in their own houses.

We should love our oceans and do something to them .

The Great Wall is _____ the north of China.[ ]

She’ll go there alone if I _____ free tomorrow.[ ]