The rivers will become dirtier and dirtier ______ wetake action to protect them.

Wow! You have a ticket to Xijiang!—It by my uncle. He is working in Xijiang.

Excuse me, what’s the time for Train 8201— It _____ at seven and you can wait in the hall.

Peter doesn’t know many people here.—__________.

I ___________ frustrated when I wasn’t sure of thecorrect answer.