There are quite a few old books on the shelf, but _____ of them is useful to teenagers.

—How do you find your classmates?—Most of them are kind, but ____ is so good to me as Peter.

_________ may have a chance to be successful if he tries his best.

--Could you do me a favor? --It depends on _____it is.

(2013·成都市高三二模)—Which of these resorts do you like best?—________.They are both hot and crowded.