21. —People should stop using their cars and start using public transport.
—________. The roads are too crowded as it is.
A．All right B．Exactly C．Go ahead D．Fine
22. In his speech yesterday, the teacher did give his students ____ advice on how to learn English as ___ second language.
A. an; a B. /; a C. /; the D. an; the
23. She said she had got ______ of looking at nature through dirty curtains and dusty windows.
A. interested B. tired C. grateful D. concerned
