年龄智商的公式是（）
A.A
B.B
C.C
D.D
参考答案：C
They are practicing ________ now. You can wait here. [ ]
A. swimming
B. going swimming
C. to go swimming
D. to swim
写数时，每个数字都要占有一个位置，数字所在为止表示的单位，称为“位数”
