综合题

读“北半球某地经纬网示意图”，完成下面小题。

①定义在R上的函数f（x）满足f（2）＞f（1），则f（x）一定不是R上的减函数；

②用反证法证明命题“若实数a，b，满足a²+b²=0，则a，b都为0”时，“假设命题的结论不成立”的叙述是“假设a，b都不为0”．

③把函数y=sin（2x+ $\frac{\pi }{3}$ ）的图象向右平移 $\frac{\pi }{6}$ 个单位长度，所得到的图象的函数解析式为y=sin2x．

④“a=0”是“函数f（x）=x³+ax²（x∈R）为奇函数”的充分不必要条件．

其中所有正确命题的序号为____．

    Sam's parents took her to the World Park last week. He saw Big Ben, the Tower Bridge, Disneyland in America, the CN Tower, Niagara Falls and the Sydney Opera House. His father told her Big Ben and the Tower Bridge are in London. Her mother told her Niagara Falls is in Canada and the Sydney Opera House is in Australia. He learnt about many things of the famous places around the world.