Some warm-hearted animals hibernate(冬眠).
A:needn't
B:does not need to
C:needn't to
一本物理书的质量为200____;一个鸡蛋的质量重力约为0.5____;空气的密度约为1.3____.
(Ⅰ)判断函数f(x)的奇偶性,并给出证明;
(Ⅱ)若θ为第一象限角,且f(θ+ π3 )= 23 ,求cos(2θ+ π6 )的值.