冬季某天我国三个城市的最高气温分别是﹣10℃，1℃，﹣7℃，它们任意两城市中最大的温差是[ ]

A．11℃

B．17℃

C．8℃

D．3℃

You are on watch at sea a man falls overboard on the port side, forward near No. 1 hatch. What of the following should you do first?（）.

A.Call the master

B.Put the helm hard over toward the port side

C.Sound the alarm to arouse all hands

D.Stop the engines