二、单项填空（共15小题，每小题1分，满分15分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
16. John plays basketball well, _______his favorite sport is badminton.
A. so B. or C. yet D. for
17. ----Why does the lake smell terrible? Ks5u
----Because large quantities of water in the lake . Ks5u
A. have polluted B. is being polluted C. has been polluted D. have been polluted
