David lives a very simple life ____ he has a lot of money.
Scientists say they are beginning to _____ in the fight against cancer.
As the spring comes, the flowers began to _____.
As we all know(众所周知), the dinosaur has _____.
The kids are looking forward to ______ Spring Festival.
Everyone in the class studied very hard since no one wanted to _____.A. fall down B fall off C. fall behind D. fall out