根据课文《月球之谜》判断对错。

 ①月球上满是尘土、岩石和环形山。____

 ②人类已经登上过月球。____

 ③月球表面全是水。____

 ④研究结果表明，月球上不可能出现过火山活动。____

    Everybody can suffer from stress．No matter what your age is，you can feel stressed out by things that are happening in your life．Teenagers，however，have many more opportunities to get stressed than people in any other age group．Being a teenager is hard．You are not a child any more，but you are not an adult，even though you have to deal with some very grown-up problems and decisions．Families can be one of the biggest causes of stress，such as problems with parents arguing at home．or problems with brothers and sisters．Teenagers also have a lot of stress from school，either from their teachers or from their friends．Some teenagers also feel stressed about choosing their education after high school．Getting a place at university can be very difficult and some cannot afford to go to university．The stress about getting a job when finishing school is hard for some teenagers．There are so many young people finishing school and not enough jobs for them．Sadly，there is nothing we can do to remove these causes of stress from the 1ives of teenagers，but you can learn the best way to deal with it．Talking to people is one of the best ways to deal with stress．It may sound simple，but it is true．A problem shared is a problem halved．

如图所示，在竖直面内有一以O点为圆心的圆，AB、CD分别为这个圆沿竖直和水平方向的直径，该圆处于静电场中．将带负电荷的小球从O点以相同的动能分别沿竖直平面向不同方向射出，小球会沿圆所在平面运动并经过圆周上不同的点．已知小球从O点分别到A、B两点的过程中电场力对它做的功相同，小球到达D点时的电势能大于它在圆周上其他各点时的电势能．若小球只受重力和电场力的作用，则下列说法中正确的是（   ）