关于各大洲的叙述，正确的是

A．非洲地势中部高、四周低

B．亚洲地形以高原为主，被称为“高原大陆”

C．欧洲是世界平均海拔最低的大洲

D．北美洲只有美国和加拿大两个国家

—I'm not too happy about the project．What shall we do next
—（）．Everything will be OK in the end．

A．Don't worry

B．Anything as you like

C．I'm afraid not

D. I don't think too much