题目

计算下面各题，怎样简便就怎样算。① ② ③ ④（35－63× ）÷ ⑤（ ）÷ ⑥ ÷[ ×（40％+ ）] 答案：解：① 0.45×37+4.5×1.3+0.045×500 =4.5×3.7+4.5×1.3+4.5×5 =4.5×（3.7+1.3+5） =4.5×10 =45 ② 3.6−3.6÷94 =3.6－3.6× 49 =3.6－1.6 =2 ③ 15−29+45−79 =(15+45)−(29+79) =1-1 =0 ④（35－63× 37 ）÷ 817 =（35-27）× 178 =8× 178=17 ⑤（ 56+23−34 ）÷ 124 =（ 56+23−34 ）×24 = 56×24+23×24−34×24 =20+16-18 =18. ⑥ 920 ÷[ 12 ×（40％+ 45 ）] = 920 ÷[ 12 × 65以下说法错误的是（　　）A．钠在常温下就容易被氧化B．钠受热后能够着火燃烧C．钠在空气中缓慢氧化能自燃D．钠在氧气中燃烧更为激烈