沿水平方向以速度飞行的子弹，恰能射穿竖直方向靠在一起的四块完全相同的木板，若子弹可看成质点，子弹在木板中受到的阻力恒定不变，则子弹在射穿第一块木板后的速度大小为___________         

The afternoon sun penetrated the mass of honeysuckle that covered the porch, and fell on my upturned face. My fingers lingered almost unconsciously on the familiar leaves and blossoms which had just come forth to greet the sweet southern spring.