阅读理解:阅读下列短文，然后从每题所给的四个选项(A、B、 C、和D)中，选出最佳选项。

    Mr. and Mrs. Green were going on their vacation with their children, and they had to arrive at the airport before 11:40 the next morning. “It takes us thirty minutes to get there in a car,”Mr. Green said, “so we must get ready before eleven o'clock. Don't be late.”

At ten fifty, all of them were busy doing something, but Mrs. Green wasn't. She sat quietly in a chair in the garden and enjoyed the good weather.

Mr. Green and the children were surprised, but Mrs. Green said, “Don't worry! Before I went to bed last night. I made all our clocks and watches twenty minutes ahead(提前). Now we can get to the airport early.”

人体生命活动所需的能量主要来自（    ）

将编号为1到4的4个小球放入编号为1到4的4个盒子，每个盒子放1个球，记随机变量 为小球编号与盒子编号不一致的数目，则 的数学期望是____

关于下列四幅图的说法正确的是（  ）

不等式$\left(a-2\right)x^2+2\left(a-2\right)x-4<0$对一切$x\in R$恒成立，则实数$a$的取值范围是（   ）