题目

如图，将纸片△ABC沿DE折叠，点A落在点F处，已知∠1+∠2＝100°，则∠A的度数等于( )A. 70° B. 60° C. 50° D. 40° 答案：【答案】C【解析】根据翻折不变性和三角形的内角和定理及角平分线的性质解答．∵∠1+∠2=100°，∴∠ADF+∠AEF=360°﹣100°=260°，∴∠ADE+∠AED=130°，∴∠A=180°﹣130°=50°．故选C．Mother is ill in bed. I have to ______ her at home. [     ]A. wait forB. think about C. look after