已知椭圆$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\left(a>b>0\right)$的离心率$e=\frac{1}{2}$，右焦点为$F\left(c,0\right)$，方程$a{x}^2+bx-c=0$的两个实根$x_1,x_2$，则点$P\left(x_1,x_2\right)$（   ）

将电阻为R₁=3Ω的导体与电阻为R₂的导体串联后总电阻为9Ω，则R₁与R₂并联后总电阻是

A：Hello! I'm a reporter．____

B: Sure, please.

A: What do you think of the clothes stores in town?

B: ____

A: Why do you think so?

B: Because it has the nicest clothes and the lowest prices.

A: ____

B: Let me see. Paris Fashion has the friendliest service, but the clothes there are the most expensive.

A: Some people like Katherine's. How do you like it?

B: ____

A: OK:' Thanks a lot.

B: ____

下列物质中不能在氧气中燃烧的是（　　）

完成右边进制的转化：1011_（2）=_____（10）=_____（8）．