A:doe
B:did
C:has to
D:had to
(I)用定义证明f(x)在(0,1)上是减函数;
(II)判断函数的奇偶性,并加以证明.
I gave him a book as a(n) present.
喜欢弹奏冬不拉的少数民族是( )
含羞草的叶子被碰后会合拢,这说明生物具有( )