我国实行对外开放,发展对外经济关系,必须坚持的根本基点是[ ]
A.内外联动,互利共赢
B.独立自主,自力更生
C.扩大开放领域,优化开放结构
D.“引进来”和“走出去”相结合
答案:B
一束光线从空气斜射入水面时发生了反射和折射,入射光线与水面的夹角为30度,反射光线与折射光线的夹角为83°,折射角大小为______.
Only one-fifth of Americans saw oil as the chief mason that the U.S. made a war on Iraq, but 75 percent of the French and of the Russians believed ______.
A. to B. so C. go D. do