完形填空。

    Jack is my classmate. He is my good friend. He is 1 American boy. He is from 2. He is short. He has a round face and    3 big brown eyes. His 4 is not black. It is blond (金黄色的). Tom likes English. He can speak a little Chinese, too. He goes to school 5 foot.

    We usually 6 our homework at school. We clean our classroom 7 every Friday. Usually, Tom 8 the blackboard and I sweep the floor. Our favourite sport is basketball. Sometimes we 9 in the playground. We 10 at 4.30. We both like our teachers and classmates.

车载GPS导航仪是通过与导航卫星互相传递信息，确定汽车的准确位置，并在电子地图上显示出来（如图），为汽车驾驶员导航．下列说法正确的是（    ）

已知集合A、B、C且A={直线}，B={平面}，C=A∪B，若  a∈A，b∈B，c∈C，有四个命题①$\left.\begin{array}{c}a\mathit{\parallel }b\\ c\mathit{\parallel }b\end{array}\right\}\Rightarrow a\mathit{\parallel }c$②$\left.\begin{array}{c}a\perp b\\ c\perp b\end{array}\right\}\Rightarrow a\mathit{\parallel }c$③$\left.\begin{array}{c}a\mathit{\parallel }b\\ c\perp b\end{array}\right\}\Rightarrow a\perp c$④$\left.\begin{array}{c}a\perp b\\ c\mathit{\parallel }b\end{array}\right\}\Rightarrow a\perp c$其中所有正确命题的序号是（ ）