Are these ____maps? Yes, they are.                  （   ）

阅读短文，选择正确的答案。

    Chen Jie and Chen Lin are sisters. Chen Jie is 14. She's 2 years younger than Chen Lin. But she's taller than Chen Lin. Chen Jie is 46 kilograms. She's l kilogram heavier than Chen Lin. Chen Jie likes sports. She plays sports every day. So she's stronger than Chen Lin. Chen Jie has short hair, but Chen Lin has long hair. They often wear the same size shoes. They wear size 36. They love each other.

直三棱柱ABC﹣A₁B₁C₁中，底面是正三角形，三棱往的高为$\sqrt{3}$，若P是△A₁B₁C₁中心，且三棱柱的体积为$\frac{9}{4}$，则PA与平面ABC所成的角大小是（　　）

读下图，做练习。

图中，能说明电动机工作原理的是（　　）