The first textbooks ______ for teaching English as a foreign language came out in the 16th century.
During the Spring Festival, the police are ______ the public safety.
He is a man of great help, with ________ help you can solve the problem easily.
We saw a ________ big snake in the grass yesterday, which ________ all of us to death. A. frightened; frightened C. frightened; frightening C. frightening; frightened D. frightening; frightening
— Tom, could you go to the supermarket with me? — I’d like to, but my homework ______ and I have to hand it in tomorrow.
Special attention should be paid to ________ forests from fires in winter.