在桌面上的书本，受到“桌面对它的支持力”这个力的施力物体和受力物体分别是（　　）

$\frac{1}{3}$ × $\frac{1}{2}$ ____ $\frac{1}{3}$             $\frac{1}{4}$ × $\frac{1}{3}$ ____ $\frac{1}{4}$

$\frac{1}{2}$ ×1____  $\frac{1}{2}$               6× $\frac{1}{2}$ ____6

9× $\frac{7}{2}$ ____9           $\frac{1}{2}$ × $\frac{2}{2}$ ____  $\frac{1}{2}$

$\frac{1}{3}$ × $\frac{1}{4}$ ____ $\frac{1}{3}$             3× $\frac{4}{5}$ ____3

$\frac{3}{4}$ × $\frac{3}{4}$ ____ $\frac{3}{4}$             5× $\frac{1}{3}$ ____5

Taste the orange,         is it? - It's sweet and sour.