在哪个方向，碰后速度为多少？
In what direction and what will be the speed after the collision?
用完后容器要安全地存放在小孩碰不到的地方。
但将液滴置于指尖后，其传染性比未经触碰的液滴降低了。
But smearing flu droplets over the fingertip reduced their infectiousness compared with untouched droplets, the study found.
应用推荐