However, in ______ recent years, Niagara Falls have come to be appreciated more for their natural beauty as ______ wonder of nature.

A．不填; a

B．the; the

C．不填; the

D．the; a

有“黑人故乡”之称的是（　　）

A．撒哈拉以南的非洲

B．大洋洲

C．拉丁美洲

D．欧洲