[填空题]
A stone is dropped from pueok vz2x(o:yz 5ckg*w4 ;my*l hl/8 thn wy;(rvbq57,4 liwatg3z; r8 zl-ic pe roof of a building; 2.20 s after that, a second stone is thrown straight dowr4rw za-;ti3b ;7v,lngc iy5z 8qlp w(n 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? $m/s$