Though I haven't seen her for many years, I recognized her at the first _____. [ ]

A. sense

B. sign

C. look

D. sight

以下是房地产经纪合同主要特征的是：( )。

A．房地产经纪合同属于单务合同

B．房地产经纪合同是双务合同

C．房地产经纪合同是有偿合同

D．房地产经纪合同是从合同

E．房地产经纪合同一般为书面形式的合同