[填空题]
A stone is dropped from the r- r vuy6-h* ,hnuvfb2iq*z) usoof of a building; 2.20 s after th)ibk o9asmez5kyy+ 3 15pun1 hat, a second stone is thrown st e+b351u ni)khyz9y1mksp oa5raight down with an initial speed of $25 \; m/s$ and the two stones land at the same time. (a) How long did it take the first stone to reach the ground? $s$ (b) How high is the building? $m$ (c) What is the speed of the first stone just before it hit the ground? $m/s$ (d) What is the speed of the second stone just before it hit the ground? $m/s$