题干
Look! A little boy ________ a horse over there. It's dangerous.
A：rides
B：is riding
C：was riding
D：has rode
答案(点此获取答案解析）
B
Look! A little boy ________ a horse over there. It's dangerous.
A：rides
B：is riding
C：was riding
D：has rode
的最小值为n，则二项式
的展开式中的常数项是 ( ）