It’s very kind ______ you to show me the way.
The conference has been held to discuss the effect of tourism(旅游业) ___ the wildlife in the area.
Sandra was a student ____ the age of 21.
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 _____.