若f（x+2）=x，则f（3）=______．
∵f（x+2）=x，
∴f（3）=f（1+2）=1．
故答案为：1．
促进水钠排泄的激素是
A．人绒毛膜促性腺激素B．人胎盘生乳素C．雌激素D．孕激素E．前列腺素
About 35% of the garbage in Hong Kong can________ every year while the rest can’t.
A. recycled B. be recycled C. recycle
