在练习打活动靶时,靶的运动方向与射击方向垂直,已知子弹的速度是800m/s,靶的速度是8m/s,在100m处射击,为射中,应在靶到达射击点前多远时开枪?
We all know that we’ll meet all kinds of difficulties in our lives in the future. We should learn to be ________ any challenge!
1840年____ 发动侵华战争,史称(____ )。
—— Dad, where is Mom?—— She the supermarket.