解方程：3$A_x^2$+$C_x^1$﹣8=0．

下列说法正确的是(    )

如果盖盖玻片的方法不恰当，很容易出现气泡，影响观察效果．下列四种盖盖玻片的方法中，最不容易出现气泡的是（图中半扁圆形结构代表水滴，箭头代表盖盖玻片的方向）（  ）

    A train stops at a station(车站). A young man wants to come out, but it is raining. A boy is standing under a big umbrella. The young man says to the boy，"Can you go and get us two hamburgers, one for you and one for me? Here are two dollars. " "Great！"says the boy and he goes to buy hamburgers. After some time, the boy is back. He is eating a hamburger. "Where is my hamburger？"asks the young man. "Oh, there is only one hamburger left(剩下). So I'm eating mine. Here is your dollar. "