People have cut down many trees every year, so there will be fewer trees, ________?
The mobile phone has influenced people's life a lot since it __________.
-What do you think of the young woman singer?-It's hard to say, but her voice __________ beautiful.
To his surprise, Jack got a low __________ in the final exam.
He practices __________ English every day.
I __________ my pen everywhere, but I didn't find it.