一、 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。
1. It’s great fun to play with Lego Robot in the training camp. How I wish I could come here for ____second time!
A. / B. a C. an D. the
2. --- Thousands of Chinese children play the piano at present.
--- Oh, I think learning a musical ____guides a child to an understanding of music.
A. introduction B. invitation C. instrument D. instruction
3. The pyramid of Khufu is so huge. It is _____ 16 Empire State Buildings.
A. so heavy as B. as heavier as C. as heavy as D. so heavier as
