Not "How much apples do you want?" — say "How many apples do you want?". 苹果是能数的（one, two, three），所以用 How many。
试一试: ___ students are in the class? (How many / How much) 答案: How many — 学生是能数的（one, two, three），所以用 How many。How much 留给不能数的东西。
How much：不能数的东西
How much 用在不能一个一个数的东西上：water, time, rice。
How much water do you drink?
How much time do we have?
How much rice should I cook?
Not "How many water do you drink?" — say "How much water do you drink?". 水没法一个一个数，所以用 How much。
试一试: ___ water do you drink each day? (How much / How many) 答案: How much — 水没法一个一个数，所以用 How much。How many 是给能数的东西用的，比如几杯水。
容易搞混的几个词
有几个词感觉上能数，其实不能，所以要用 How much：money, time, homework, advice。多练习自然就会有感觉。
How much money do you need?
How much homework do you have?
How much time do we have?
试一试: ___ money do you have with you? (How much / How many) 答案: How much — 钱感觉上能数，但英语里不能一个一个数，所以用 How much。（这些容易搞混的词，多练习就好了。）
试一试: Can you count it? ___ chairs do we need for the party? (How many / How much) 答案: How many — 椅子是能数的（one, two, three），所以用 How many。（能数 → many；不能数 → much。）