定义运算 $\begin{array}{cc}a& c\\ b& d\end{array}$ $\begin{array}{c}x\\ y\end{array}$=$\begin{array}{c}ax+cy\\ bx+dy\end{array}$，称$\begin{array}{c}x\text{'}\\ y\text{'}\end{array}$=$\begin{array}{cc}a& c\\ b& d\end{array}$$\begin{array}{c}x\\ y\end{array}$为将点（x，y）映到点（x′，y′）的一次变换．若$\begin{array}{c}x\text{'}\\ y\text{'}\end{array}$=$\begin{array}{cc}2& -1\\ p& q\end{array}$ $\begin{array}{c}x\\ y\end{array}$把直线y=x上的各点映到这点本身，而把直线y=3x上的各点映到这点关于原点对称的点．则p，q的值分别是（　　）

Opposite our school ______, where a lot of people play or take exercise at any time.

植物体的薄壁组织具有储存营养物质的作用．（判断对错）

32.4－1.8×18=____