公共建筑空间组合中的通道的宽度与长度，主要根据功能需要、防火规定及（）来决定。
参考答案：建筑空间处理的需要
一船在静水中的划行速率为5m/s，要横渡一条宽30m、流速为3m/s的河流，此船渡河的最短时间为 s，此船渡河的最短航程为 m。
Detective Johnson wanted to find out_______.
A．where was the witness that day
B．where has the witness gone the day before
C．where the witness was that day
D．where the witness has gone the day before
