题目

递等式计算（能简算的要简算） ①4.65﹣2.55﹣1.45②6.4÷（0.3×2+0.2）③6.5×99④2.2×0.25+2.8×0.25． 答案：解：①4.65﹣2.55﹣1.45 =4.65﹣（2.55+1.45）=4.65﹣4=0.65；②6.4÷（0.3×2+0.2）=6.4÷（0.6+0.2）=6.4÷0.8=8；③6.5×99=6.5×（100﹣1）=6.5×100﹣6.5=650﹣6.5=643.5；④2.2×0.25+2.8×0.25=（2.2+2.8）×0.25=5×0.25=1.25．根据句意和提示写单词 They talked and laughed the ________/hul/ afternoon.