There will be trees and pollution in the future.

About _________ of the teachers in tour school were born in ________.

We’ll make a trip to Hainan Island next weekend. Will you go with us?—No, I can’t _____ it at present.

Polly’s mother was anxious about ______ she could get home safely in ______ foggy a day.

Is this ___________ruler?—No.________________is over there.