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14分，每小题1分）
1. Yesterday Shirley advised me to buy my daughter _________ iPad as a birthday present.
_________ useful advice she offered me!
A. a; How B. an; What a C. an; What D. /; How an
2. The doorbell is ringing. It _________ Alice , because she__________ Washington.
A. can’t be; has gone to B. may be; has been to
C. mustn’t be; has gone to D. can’t be; has left to
3. Though they are______little children , they have worked out _______many difficult math problems.
A. so; so B. such; such C. so; such D. such; so
