在地面上以初速度<img src="https://static.zxtiku.com/wangke/imgs/topic/acdf23da3347720b5f53a1545b2406da.jpg"/>,抛射角<img src="https://static.zxtiku.com/wangke/imgs/topic/7497a13dd02a50dc638b834d531065d6.jpg"/>斜向上抛出一物体,不计空气阻力。经过多长时间后,速度的水平分量和竖直分量大小相等,且竖直分速度方向向下?( ) A. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/01bcc05a56c4e677d1de617f1f0a6bfa.jpg"/> B. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/ca525a4ca325a6de2a46e274ffd61fa2.jpg"/> C. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/e4ea30e4c75e122ed92d4311325e6f65.jpg"/> D. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/a31e3ccea0ddfbefff08f98eff4308e7.jpg"/>