64seconds
9 ]7 o4 D, G3 }$ R k公仔箱論壇0 _. Q& [, P+ i: y, `$ n
1 to 4 have 3floors = 48 sec
" L# `2 Y) g' _: f; Y+ u0 Yavg. 48/3 = 16sec
7 ~9 }, P7 d% a* ^
3 ?4 o% S$ |" K" A0 d+ J9 O2 dtvb now,tvbnow,bttvb4 to 8 have 4floors = 16x41 h, z, n' F. ]% v1 X* N4 H* B
= 64secs |