You ____ pale. What's wrong with you?

在太空的国际空间站划燃火柴，火柴过一会儿会熄灭，原因是（   ）

⑴Did you buy some water?____          A、I live in Beijing.

⑵Where do you live?____                    B、Yes, It will.

⑶Who are they?____                            C、They are my grandparents.

⑷What's this?____                                D、No, we bought a watermelon.

⑸Will it be windy in Tianjin?____         E、It's a robot.

对$\forall a,b\in R$，运算“$\oplus$”、“$\otimes$”定义为：$a\oplus b=\left\{\begin{array}{c}a,a<b\\ b,a\ge b\end{array}\right.$，$a\otimes b=\left\{\begin{array}{c}a,a\ge b\\ b,a<b\end{array}\right.$，则下列各式其中不恒成立的是（    ）
⑴$a\otimes b+a\oplus b=a+b$    ⑵$a\otimes b-a\oplus b=a-b$
⑶$a\otimes b·a\oplus b=a·b$   ⑷$a\otimes b÷a\oplus b=a÷b$