使用海锚可减缓救生艇（筏）的漂流速度，保持弃船后救生艇筏能在遇难海域附近停留（）以上，等待救援。
A.12h
B.24h
C.48h
参考答案：B
“三北”防护林又称绿色万里长城，“三北”防护林体系不包括的省区有( )。
A．黑龙江
B．山西
C．河南
D．青海
I’m just wondering ___ I first met Tom.
A．where it was that
B．that was it where
C．where was it that
D．that it was where
