各种流通组织和当事人是商品流通网络的__________。
参考答案：主体
Excuse me! Do you know ___________ the post office is?[ ]
A. who
B. what
C. where
D. how
—Do you like red and green?
—Yes．They’re my ________ colors．
A．healthy
B．right
C．last
D．favorite
