某旅店一共70个房间，大房间每间住8个人，小房间每间住6个人，一共480个学生刚好住满，设大房间有 x个，小房间有 y个．下列方程组正确的是（　　）

A．	$\left\{\begin{array}{c}x+y=70\\ 8x+6y=480\end{array}\right.$	B．	$\left\{\begin{array}{c}x+y=7\\ 6x+8y=480\end{array}\right.$
C．	$\left\{\begin{array}{c}x+y=480\\ 6x+8y=70\end{array}\right.$	D．	$\left\{\begin{array}{c}x+y=480\\ 8x\text{+6}y=70\end{array}\right.$