Hamburgers and ice cream are unhealthy food.这句强调Hamburgers 和 ice cream属于不健康食物，因此food为不可数。
Coke is an unhealthy drink. 这句加了冠词an，强调Coke（可口可乐）是一种不健康饮料，因此drink是可数的。
drink的用法：
一、用作名词
drink作“饮料”解时，可指矿泉水、柠檬茶等不含酒精的软饮料(soft drink)，也可指啤酒、白酒等含酒精的硬饮料(hard〔strong〕 drink)，还可指热茶、咖啡等温度较高的热饮料(hot drink)，作此解时是不可数名词；而作“一杯杯的饮料”解时，是可数名词。
drink还可作“酒”解，尤指白酒。泛指酒时，是不可数名词；而指“一杯一杯的酒”或“各种酒”时是可数名词。
二、用作动词
drink的基本意思是“用嘴直接喝、饮”,可以用于任何可以喝的东西,如水、茶、酒、咖啡、柠檬汁等。
drink用作及物动词时可接名词或代词作宾语，还可接形容词或介词短语作宾语补足语。用作不及物动词时常指“喝酒”，有时也可表示“喝水”。
英语泛指“喝酒”只说drink,不说drink wine; “喝一杯?”一般用have〔take〕 a cup of...,不用drink a cup of...。
扩展资料
一、drink, have, take
这三个词的共同意思是“吸”或“饮”。其区别是：
1、就宾语来说,这组词都可指喝酒、饮料或水; have还可指吸烟; take还可指吸烟和呼吸新鲜空气。
2、就方式来说, take和have可用任何方式; 而drink通常指用嘴直接喝,而不用勺、匙或吸管。
3、drink还可引申表示“吸取”知识。
二、drunk, drunken
drunk和drunken都是drink的过去分词形式。其区别是：
1、drunk可以用作表语, drunken只用作定语; 在当代英语中, drunk也可用作定语。
2、drunk作定语的意思是“偶尔喝醉的”; 而drunken则指“经常喝醉的”
[英][drɪŋk][美][drɪŋk]
vt.& vi.喝（酒）; 饮; 喝酒; （尤指）酗酒;
vt.吸收，吸入;
n.酒，饮料; 酒宴; 一杯或一份酒;
第三人称单数：drinks过去分词：drunk复数：drinks现在进行时：drinking过去式：drank
drink
n.
ADJ. cold, cool, iced, refreshing I could do with a nice cool drink. | hot, warm | milky | fizzy | low-alcohol, non-alcoholic, reduced-alcohol, soft | alcoholic | stiff, strong | diet, low-calorie | long She took a long drink of cold water. | celebratory | welcome You will be offered a welcome drink on arrival at the hotel. | farewell | early-evening, lunchtime | leisurely We were enjoying a leisurely drink before dinner. | quick | quiet
QUANT. round We ordered a round of drinks while waiting for a table.
VERB + DRINK drink, have I'll just drink my drink then we can go. She had a hot drink and went to bed. | sip | down, finish, knock back He knocked back his drink in one go and ordered another one. | take He took a drink of his beer and sat down. | go for Would you like to go for a drink after work? | buy (sb), get (sb), offer (sb), order (sb) Can I buy you a drink? | pour (sb), serve (sb) He poured himself a stiff drink to calm his nerves. | spike The robbers spiked his drink before taking his wallet and passport. | drive sb to Her money problems drove her to drink (= made her start drinking a lot of alcohol). | turn to After his wife died, he turned to drink.
DRINK + NOUN drinks party We've been invited to a drinks party. | drinks cabinet/cupboard She took a bottle from the drinks cabinet. | problem She suspected her boss had a drink problem.
PREP. in a/the ~ Do you want ice in your drink? | ~ of I'll have a drink of milk, please.
drink
v
1 take liquid into the body
ADV. greedily I pulled the ring-top from the can and drank greedily. | down, up He filled a cup with water and drank it down in one gulp. Drink up, and let's go home.
VERB + DRINK get yourself sth to, find sth to, have sth to Go and get yourself something to eat and drink.
PREP. from He drank from a tumbler. | through drinking lemonade through a straw
PHRASES eat and drink
2 drink alcohol
ADV. excessively, heavily, to excess, too much He's been drinking heavily since he lost his job. | in moderation, moderately, sensibly One way of persuading people to drink sensibly is to provide good-tasting alternatives with less alcohol. | steadily She had been drinking steadily since the early morning.
PHRASES drink and drive The campaign aims to persuade people not to drink and drive. | drink like a fish (= drink a lot) Simon was drinking like a fish that evening. | drink yourself to death He knew that he was probably drinking himself to death.
参考：牛津词典本回答被网友采纳
和fruit这两个单词一般情况下都不可数，不是表示种类时可数，而是在表示有多种种类的饮料，fruit的时候可数，用复数。food一直不可数
drink的用法详解