七大洲中，面积最大和最小的分别是（　　）

A．非洲　北冰洋

B．亚洲　印度洋

C．亚洲　北冰洋

D．北美洲　大西洋

What would have happened ________, as far as the cliff?

A．if Bob has walked farther

B．if Bob should walk farther

C．if Bob had walked farther

D．if Bob walked farther