“Early to bed, early to rise（起身）makes people healthy, wealthy and wise（健康，富有，聪明）.” This is an old English saying. Children should have ten hours' sleep every night, or they can't do their work very well. They will not be wise. The body needs exercise. Walking, running, swimming and playing ball games are all exercise. Exercise keeps the body strong.

一个物体静止在光滑水平面上，在0～t₀时间内给物体施加一个水平向右的拉力F，该力随时间的变化规律如图所示．下列说法正确的是（   ）

自信为我们搭起了一个人生的平台，使我们可以（　　） 　
①主动积极地应对生活中的各种问题     ②使我们保持心情宁静

③使我们从容地享受生活的乐趣             ④实事求是地看待自己，既能看到自己的优点，也能看到自己的缺点