如图，在四棱锥 $S-ABCD$ 中，底面梯形 $ABCD$ ， $AD\parallel BC$ ，平面 $SAB\perp$ 平面 $ABCD$ ， $\Delta SAB$ 是等边三角形，已知 $AC=2AB=4$ ， $BC=2AD=2CD=2\sqrt{5}$ ， $M$ 是 $SD$ 上任意一点， $\stackrel{\rightharpoonup }{SM}=m\stackrel{\rightharpoonup }{MD}$ ，且 $m>0$ .

“三个代表”重要思想是***的立党之本，执政之基，力量之源。它创造性地回答了（  ）

阅读理解B
    Are friends important to you?They are really important to me．My name is Phil and I'm 13．I'm from London．I have a very good friend.His name is Max．
    Max and I have a lot ofthings in common(有共同之处):our birthdays are on the same day；we are in the same class；we both love dogs；we are both good at sports and soccer is our favorite…. We always have a good time together．
    But these days I'm not happy．Max will leave England，because his father gets a job in Shanghai．Max's family will go there．I have a lot to talk with Max．and I want to give him an album(相册)．There are a lot of our photos in it．
    Today is Monday．There are only three days before Max leaves．I will go to his home to give him the album this evening．
根据材料内容简要回答下列问题。

下列反应不属于可逆反应的是(　 　)。

如图，根据平面镜成像特点，画出物体MN的像M′N′。（要求：保留作图痕迹）