21. _______to sunlight for too much time will do harm to one’s skin.
A. Exposing B. Being exposed C. Having exposed D. Exposed
22. With a MBA degree from Harvard University, our boss takes a______ method to manage the company, which benefits everyone a lot.
A. consistent B. violent C. scientific D. rough
23. Copernicus’s theory is now the basis ______ all our ideas of the universe are built.
A. to which B. on which C. for which D. by which
