Alex Palmer Haley (1925―1992) became famous for the publication of the novel Roots, which traces (追踪) his ancestry (祖先) back to Africa.Alex Haley was born in Ithaca, New York. His father was
I feel it hard to keep up with my classmates in study and sometimes I lose heart. But whenever I want to , my teacher always encourages me to work harder. A. go on B. run aw
的一个单调递减区间是（ ）
B．
C．
D．
，令
，解得：
，令
可得函数的一个单调递增区间为
.故选B .