一个等边三角形的边长是9厘米，它的周长是____厘米。

设函数$f\left(x\right)=\left\{\begin{array}{c}{2}^{-x}-1,x\le 0\\ x^{\frac{1}{2}},x>0\end{array}\right.$若$f\left(x_0\right)>1$，则$x_0$的取值范围是(     )

秦朝建立后，秦始皇推行了一系列巩固“大一统”的举措，其中包括（　　）

①统一车辆形制   

②统一文字     

③统一货币     

④统一度量衡

阅读短文，判断下列句子是否符合短文内容，符合的写正确，不符合的写错误。

     Jim lives in a city with his wife. He is a police officer. He works in a police. It is not far from his home, so he goes to work on foot every day. His wife is a worker, she works in a factory. It's far from her home, she goes to work by car. When she drives the car, she is very careful. When the light is red, she stops. When the light is yellow, she waits. She won't go until the light is green. She always says that we must obey (遵守)the traffic rules.