1. (2018五上·东莞期中) 计算下面各题，能简便的要用简便方法算。

①1.25×0.73×0.8

②4.37×0.55+5.63×0.55

③0.25×4÷0.25×4

④63.4÷2.5÷4

⑤10-6.48÷1.8

⑥2.1×[（4.5+1.5）÷0.05]