21. Living in _______ ever increasingly fast-paced world, we are facing greater competition, so we must take _______ advantage of every opportunity to develop.
A. an; the B. an; 不填 C. the; an D. the; 不填
22. I am _______ about what I say because careless remarks are likely to hurt others’ feelings.
A. enthusiastic B. concerned C. doubtful D. cautious
23. — That must have been a terrifying experience.
— Yeah. I _______ in the damaged car, unable to move.
A. was stuck B. have been stuck C. am stuck D. had been stuck
