12×47= ____
12+13= ____
23×23= ____
16×29= ____
Anyone who has spent time with children is________of the difference in the way boys and girls respond to similar situations.
我国“南米北面”的传统饮食习惯,体现了农业生产的( )
泡菜具有独特的风味,适合制作泡菜的食盐水浓度是4%.在配制4%的食盐水2000g时,下列做法:①用80g食盐和2000g水配制溶液;②称量食盐时(1克以下用游码),食盐放在右盘的纸上;③量水的体积时,俯视量筒;④溶解食盐的烧杯内壁是潮湿的;其单一错误会导致溶液浓度偏小的是 ____ .