温度升高30℃，记作+30℃，温度下降30℃，记作﹣30℃． ．
×= ÷=0.2× =25× =1．
12个是 ，27×=27÷ × ．
4×=÷3=====
×= ÷=0.5× =15× =1．
50的是18的．
= ÷
=0.2× =25× =1．
是 ，27×
=27÷ × ．
=
÷3=
=
=
=
=
= ÷
=0.5× =15× =1．
是18的
．
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