画一画、量一量．（1）画一画，150度．（2）如图，∠1= ．
= ．
1﹣= ．
1+3= ．
口算 55+37= 80﹣26= 1400﹣800= 2+210= 9+300= 82+0= 1﹣= += ﹣= ．
= ．
= ．
+3= ．
= ．
= 
+
= 
﹣
= ．
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