计算
①÷[×（+）]                          ②（0.4+）÷（﹣0.75）×0.5
③1.25+×7.4+125%÷                      ④
⑤6.6﹣÷（0.375×+×0.8）                 ⑥﹣2.125+（4.75﹣）
⑦+[（1.5+）÷3.75﹣]÷              ⑧+++…+．