买菜说成buy vegetable不能说错，只是不地道，因为native English speaker不这么说。
我们买菜当然是去菜市场，地摊，要么超市。As far as I know, 老外买菜要么去supermarket，要么去grocery store。grocery store给我第一反应是杂货店，小超市的感觉。来看看牛津词典对grocery的解释：
(especially British English) (North American English usually grocery store) [可数名词] a shop/store that sells food and other things used in the home. In American English ‘grocery store ’ is often used to mean ‘supermarket ’. 食品杂货店（在美国英语中grocery store常用以指supermarket）
再听听Englishpod主播对groceries的解读：
Groceries are all of the food items you need to buy at the supermarket, so like your bread and milk and meat and vegetables...
Examples:
There's no milk. Can you go to the grocery store?
Here's the grocery list. I need all of these things, so that I can cook dinner tonight. Don't forget anything.
I hate grocery shopping. I can never find what I'm looking for.
另外，grocery美国英语和加拿大英语还有一点点区别，看对话：
A（加拿大人）: You know, grocery store, I think this is quite a common word in Canada.
B（美国人）: Probably in north America.
A: Yeah, do you say gorcery store in America?
B: Well, if it's a small one.
A: Really, so...
B: Like a small store.
A: In Canada, I say grocery store for even like a super market.
B: Really?
A: Yeah.
B: I guess, mm, I would say supermarket for a large one and grocery store for a little corner shop.
A: All of these little differences in American and Canadian English.
B: Hehe.
”今天谁买菜？“这是我经常对老婆说的一个高频句，看Englishpod原文中的两句：
I'll do the dishes and get all the groceries for tonight.
I'll go to the supermarket and get all the groceries.
”买“是get，不是buy；”菜“是 groceries而非vegetable。还有第一句中的”洗碗“的洗不是wash而是do，这是英汉思维（习惯）的区别，很多时候，汉语用具体的下意词，而英语用抽象的上意词。字面上，英语更合逻辑些，groceries涵盖各种吃的，汉语用一个＂菜＂代表了做饭所需的各种，如果按字面只翻译vegetable，＂菜＂所代表的约定俗成的含义就译不出，万一你还要买豆腐和肉类呢。
"今天谁买菜？"是不是可以这样说：
Who's gonna get all the groceries for tonight?