防虫的关键温度是（）
A.20℃
B.40℃
C.35℃
D.15℃
E.10℃
参考答案：D
函数f（x）=log0.5（3x2-ax+5）在（-1，+∞）上是减函数，则实数a的取值范围是 ．
We have heard what he has said; we are waiting to see he will do. [ ]
A．how
B．what
C．when
D．that
