The Smith’s family, which __________ a large one, ____________visit BeiJing this summer.
The scientists are now trying to discover what use could be ____ such material.
This tree looks high and strong but ____ its trunk is hollow.
—Smoking is bad for your health. — Yes, I know. But I simply can’t ____.
– Do you know the West Lake in Hangzhou? – Yes, this is the third time that I ____ this beautiful city.
We’ll have to finish the work, ____.