A:earn more money
B:do her job for the United Nations
C:celebrate an art festival
D:make paper cutting well-known
“黄河之水天上来,奔流到海不复回”诗中“天上”和“海”分别是指( )
设a∈R,函数fx=ex+ae-x的导函数是f,x,且f,x是奇函数,则a的值为( )