如图所示,在抗洪救灾中,一架直升机通过绳索,用恒力F竖直向上拉起一个漂在水面上的木箱,使其由水面开始加速上升到某一高度,若考虑空气阻力而不考虑空气浮力,则在此过程中,以下说法错误的(         )

读下图，做练习。

下列各对数中，互为相反数的是（   ）

    Everyone knows that exercise is important. We all need to exercise. Doctors say it's good for us. It keeps body strong.

    When the daytime comes, we must get up. This is the time for exercise. Exercise means doing things with the body. There're many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you exercise in the following(下面的)ways: You have to like what you're doing. Exercise enough—but not too much. It's good to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or three sports that feel right for you.

    Exercising can be fun. Friends can exercise together at a fitness center, or they can play sports together. How do you exercise?

根据短文内容，选择正确答案。