Before I left home, my mother taught me ________some simple dishes, such as noodles and garlic with vegetables.

A．what cooking

B．how cooking

C．what to cook

D．how to cook

化学知识中有很多的“相等”。请你判断下列说法中正确的是

A．溶液稀释前后，溶质的质量相等

B．10mL酒精和10mL水混合，所得溶液体积等于20mL

C．电解水时正负极产生的气体体积之和等于电解掉水的体积

D．两饱和的KNO₃溶液降低相同的温度，析出的KNO₃质量一定相等