A:90度
B:66度34分
C:43度8分
D:46度52分
—There's a(n) _______ map in my car. It even can tell us which way is less crowded.
(Ⅰ)求f(t)的单调减区间;
(Ⅱ)求证:f(t)+f(t+2)+f(t+4)是定值.
甲常说:“我是万能输血者.”乙却说:“我是万能受血者”.请你分析一下,甲、乙的血型分别是( )