Reducing the gap between rich and poor is one of the main _______ facing the governmen

继续教育 专四 已帮助 人

Reducing the gap between rich and poor is one of the main _______ facing the government.

A、chances

B、challenges

C、chains

D、changes

热搜:n维列向量组a1,an-1线性无关,且与非零向量正交