A:
B:
C:
D:
实验步骤如下:
Ⅰ.检查装置的气密性;
Ⅱ.向装置A中通入过量的CO2气体,关闭弹簧夹;
Ⅲ.滴加浓硝酸;
……
23×20=____ 300÷5=____ 31×20=____ 210÷7=____ 2.9-1.5=____
Some children in Jiangxi, China, go to school ________.
There ____ ____ meat in the fridge.