下列省区具有两个简称的是[ ]

A．黑龙江省

B．海南省

C．云南省

D．广西壮族自治区

The controlling depth of the river is（）.

A.the minimum depth of the river prescribed in the channel maintenance program

B.the edge of a dredged channel

C.the highest level to which the river may rise without flooding

D.the least available water in a channel which limits the draft of boats and tows