要想使电荷流动起来形成电流，需要具备两个条件：一是要有____，也就是____；另一个是要有____电流只有在电路中才能流动。

如图甲所示，为我国自主研制、全球最大的两栖大飞机AG600漂浮在水面时的情景，AG600飞机能够像船一样在水面滑行、起飞降落．它的用途很多，最主要的是森林灭火、水上救援、物资运输、海洋探测等．该飞机最大总质量为53.5吨、机体总长36.9米，翼展达到38.8米，4台发电机，单台功率为3126km，航程4500km，一次可救护50名遇险者．如图乙所示为我国自主研制的“海斗号”无人潜水器，最大下潜深度科大10767m，取海水的密度为1×10³kg/m³．

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    Last summer, as soon as school was over, I thought maybe I could spend the summer ____ a way different from previous ones. But how? Perhaps I could take____part-time job and make some money. I ____ (offer) an interview soon after I filed my application to Kentucky Fried Chicken. The interview was three days ahead. ____ (prepare) for it, I went through Interview Skills, a book ____ prepares readers for job interviews. My mom and dad tried to help by ____ (give) me simulated (模拟的) interviews one after ____I was all ready the day before the interview.

    I answered all of the manager's questions ____(perfect). After all, my mom and dad had expected all of them and I just needed to repeat the answers I had prepared. Besides, I had carried myself well through the interview. My facial ____(express), my voice, my…… all were excellent. I felt the job was already mine. That night I calculated how ____ money I would make, and I planned the ways I would like to spend it.

如图所示为氢原子的能级示意图，一群氢原子处于n=3的激发态，在向较低能级跃迁的过程中向外发出光子，用这些光照射逸出功为2. 49 eV的金属钠，下列说法正确的是

现从某医院中随机抽取了7位医护人员的关爱患者考核分数（患者考核：10分制），用相关的特征量 $y$ 表示；医护专业知识考核分数（试卷考试：100分制），用相关的特征量 $x$ 表示，数据如下表：

特征量	1	2	3	4	5	6	7
$x$	98	88	96	91	90	92	96
$y$	9.9	8.6	9.5	9.0	9.1	9.2	9.8

附：回归直线方程 $\widehat{y}=bx+a$ 中斜率和截距的最小二乘法估计公式分别为

$b=\frac{{\sum }_{i=1}^n\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)}{{\sum }_{i=1}^n{\left(x_i-\overline{x}\right)}^2}$   ， $a=\overline{y}-b\overline{x}$  .