题目

Are you always embarrassedat social events？Or do you often struggle (挣扎)to enter into conversations because you are shy？If so，your social life and career may have been influenced in some way. 【1】Then，you’ll be able to enter into conversations with confidence.Behave like a social person. You can behave like a more social creature even if you don’t feel like it. Don’t allow anxiety to hold you back. Make the decision to talk to new people andenter into conversations even when you’re feeling nervous about it.【2】Create goals for yourself.【3】Perhaps you want to pract如右图所示，一小球以初速度v0沿水平方向射出，恰好垂直地射到一倾角为30°的固定斜面上，并立即反方向弹回。已知反弹速度的大小是入射速度大小的，则下列说法正确的是                             （     ） A．在碰撞中小球的速度变化大小为 B．在碰撞中小球的速度变化大小为 C．小球在竖直方向下落的距离与在水平方向通过的距离的比为 D．小球在竖直方向下落的距离与在水平方向通过的距离之比为