shícái mǎiqí le.

食材 means ingredients for cooking—the edible items you use to make a dish, such as vegetables, meat, tofu, mushrooms, and so on.

It does not usually mean finished food in the general sense. It is closer to cooking ingredients than to a meal.

A useful comparison:

• 食物 = food in general
• 饭菜 = cooked dishes / meal
• 材料 = materials; can mean ingredients, but is broader
• 食材 = food ingredients specifically

So in this sentence, 食材 refers to the ingredients that needed to be bought.

In 买齐, 齐 is a result complement.

So:

• 买 = to buy
• 齐 = complete, all together, all there

Put together, 买齐 means to buy everything needed so that the set is complete.

This is a very common Chinese pattern:

• verb + result complement

Examples:

• 找齐 = gather all of something together / get the full amount together
• 配齐 = match/prepare a complete set
• 收齐 = collect everything completely

So 买齐 does not just mean buy. It means buy all of them so nothing is missing.

They are similar, but not the same.

• 买完 = finish buying
• 买齐 = buy all the necessary items so the set is complete

The difference is about focus:

• 完 focuses on finishing the action
• 齐 focuses on having a complete set

For example:

• 菜我买完了。
  = I finished buying the groceries.

• 菜我买齐了。
  = I bought everything we needed; nothing is missing.

You can think of it this way:

• 买完 answers: Did you finish the shopping?
• 买齐 answers: Did you get all the required items?

Here, 了 shows that a new situation has been reached: the ingredients are now fully bought.

In this sentence, 了 is closely tied to the idea of completion/result:

• 食材买齐了。
  = The ingredients have all been bought now.

It does not simply mean past tense like English -ed. Chinese 了 is not just a past marker. It often signals that something has changed or a result is now true.

So the key idea is:

• before: the ingredients were not all bought
• now: they are all bought

Chinese often leaves out the subject when it is obvious from context.

So 食材买齐了。 could mean:

• I’ve bought all the ingredients.
• We’ve bought all the ingredients.
• They’ve bought all the ingredients.

The listener usually knows who is being talked about from the situation.

This kind of omission is very natural in Mandarin, especially in conversation.

In this sentence, 食材 is best understood as the thing being talked about—so it has a topic-like feel.

A natural way to understand it is:

• As for the ingredients, they’ve all been bought.

Chinese often puts the important noun first and then comments on it.

So instead of explicitly saying:

• 我们把食材买齐了。

the speaker can simply say:

• 食材买齐了。

This sounds concise and natural when the context is already clear.

Yes, 食材都买齐了 is very natural.

都 adds extra emphasis to the idea of all.

Compare:

• 食材买齐了。
  = The ingredients are all bought / We bought all the ingredients.

• 食材都买齐了。
  = The ingredients are all bought now.
  (slightly more explicit/emphatic about completeness)

Because 齐 already suggests completeness, 都 is not required. But adding it often sounds very natural in everyday speech.

Sometimes, but the meaning and feel change.

• 食材买齐了。
  = The ingredients have all been bought now.
  This sounds like a completed result.

• 食材买齐。
  By itself, this sounds incomplete or unnatural in most everyday contexts.

Without 了, the phrase often needs to appear inside a larger structure, for example:

• 等食材买齐再开始。
  = Wait until all the ingredients are bought, then start.

So in a standalone statement reporting that the task is done, 了 is normally expected.

A very natural negative sentence is:

• 食材还没买齐。

Breakdown:

• 还 = still, yet
• 没 = have not
• 买齐 = bought completely / bought all of them

So:

• 食材还没买齐。
  = The ingredients haven’t all been bought yet.

Notice that in negative sentences, you normally use 没 rather than adding 了.

It is quite natural in everyday speech and also fine in ordinary writing.

It sounds concise and efficient, which is very common in Mandarin. In conversation, people often leave out subjects and say exactly this kind of thing.

Depending on style, you might also hear:

• 食材都买齐了。
• 我们把食材买齐了。
• 食材已经买齐了。

These all express roughly the same core idea, with slightly different emphasis:

• 都 = all
• 把 = marks the object more explicitly
• 已经 = already

It is pronounced:

• 买 = mǎi (3rd tone)
• 齐 = qí (2nd tone)

So 买齐 is mǎiqí.

There is no special tone change here. You just say:

• mǎi qí

And the full sentence is:

• 食材买齐了
• shícái mǎiqí le

A small note: the 了 here is usually pronounced lightly as le, not with a full strong tone.