射频控温热凝术热凝的温度是（）
A.50℃～60℃
B.60℃～80℃
C.50℃以下
D.90℃以上
E.70℃～90℃
参考答案：B
已知f（x）=x3+2x，则f（a）+f（-a）的值是（ ）
A．0
B．-1
C．1
D．2
－What is the rich peasant’s plan?
－He has made up his mind to a home for the elderly in his village.
A．turn up
B．put up
C．set up
D．make up
