A:might it be
B:could it be
C:could it have bee
D:should it have bee
中东地区跨亚非两洲的国家是( )
看图,搭配。
A. sun B. water C. beaches D. seafood
①clear ____
②beautiful ____
③nice ____
④warm ____
设a,b,C为正数,
求证: a2+b2+b2+c2+a2+c2≥2a+b+c .