With Halloween approaching, there exists a real concern among parents and teachers __________ trick or treating will become a seriously anti-social activity.

一Where is Jason I want to tell him about the result of the singing competition.一Oh, you . He has known it already.

There were dirty marks on her trousers __________she had wiped her hands.

I still haven’t found my pet dog. —I’m sorry to hear that. You______ be very sad.

In modern civilization, mankind is destroying the planet, all __________ progress