I searched for my wallet and it wasn't there. At first, I thought I _______ it at home. Then I remembered _______ it out to pay for the taxi.

A．must have left；to take

B．may leave；taking

C．might leave； to take

D．could have left；taking

我们观察不同民族的成员之间发生的关系是否能构成民族关系时，关键是这种关系中是否具有（）的内容。