有关材料层热阻的法定计量单位，下列哪一项正确()
A．(㎡K)／W
B．kcal／(㎡h．K)
C．W／(㎡hK)
D．W／㎡
参考答案：A
Mr. Black has been teaching English in a middle school _____ he came to China.
A．for ever
B．ever since
C．since then
D．long before
( )保证了地籍资料的现势性和准确性。
A．初始地籍调查
B．变更地籍调查
C．地籍测量
D．变更地籍测量
