一、单项填空 在A、B、C、D四个选项中, 选出可以填入空白处的最佳选项。(本大题共15分，每小题1分)
1. ——Is ______________ book on the teacher’s desk _____________ useful one?
——No, it isn’t. You can throw it away.
A. the, an B. the, a C. a, the D. the, /
2. After the weather _______________ fine for several days, it snowed again.
A. seemed B. stayed C. became D. has kept
