[填空题]
A stone is thrown vertic4f oke2t nzu-4vyy r1.ally upwaxzxtzhh-) 2a *von. o0x.xc*0a8 jizord with a speed of 18.0 m/s
(a) How fast is it moving when it reaches a height of 11.0 m? |v| = m/s
(b) How long is required to reach this height? t = s, s
(c) Why are there two answers to (b)?