mada keeki o tabete imasen.

I haven't eaten cake yet.

Breakdown of mada keeki o tabete imasen.

• を: direct object particle
• 食たべる: to eat
• ケーキ: cake
• まだ 。。。 て いません: have not yet ...

Questions & Answers about mada keeki o tabete imasen.

Why is まだ placed at the beginning of the sentence? Could I put it after the object?

まだ means “still” or “not yet.” When you want to express “haven’t done something yet,” you typically place まだ immediately before the verb phrase or at the very front of the sentence. For example:

• Natural: まだケーキを食べていません。
• Less common: ケーキをまだ食べていません。

Putting まだ too far from the verb can make the sentence sound awkward or less natural.

Why do we use 食べていません instead of simply 食べません?

食べていません is the negative form of the ～ている aspect, which here expresses that the action has not occurred up to now (a perfect or resultant state).

• まだケーキを食べていません。 = “I haven’t eaten the cake yet.”

On the other hand, 食べません is the simple non-past negative (“I won’t eat” or “I don’t eat [habitually]”), so it’s not used to mean “have not eaten yet.”

What does the ～ている form mean in 食べていません?

The ～ている form can express:
• Progressive (“is doing”)
• Perfect/resultant state (“has done”)

In combination with まだ and the negative, まだ食べていません indicates the perfect aspect: the cake remains uneaten up to now. So 食べていません here means “have not eaten.”

Why is the verb at the end of the sentence?

Japanese follows an SOV (Subject-Object-Verb) word order. Verbs (and verb phrases like 食べていません) always come at the end of their clauses. That’s why you see 食べていません as the final element.

What is the role of を after ケーキ?

を marks the direct object of the verb. In ケーキを食べていません, it tells us that the cake is what’s not been eaten. Without を, the sentence wouldn’t clearly show what you’re eating (or not eating).

Why is there no subject in the sentence?

Japanese often omits the subject when it’s clear from context. Here, (私は) “I” is understood. The full version would be:
私はまだケーキを食べていません。

Could we use は instead of を, as in ケーキはまだ食べていません?

Yes. Changing を to は makes ケーキ the topic rather than just the object. This adds contrast or emphasis on the cake:

• ケーキはまだ食べていません。
  (As for the cake, I haven’t eaten it yet.)
  Using を is more neutral: you’re simply stating the action hasn’t happened.

Can I use the plain form 食べていない instead of the polite 食べていません? What’s the difference?

Definitely. The plain (informal) negative is 食べていない, while the polite form is 食べていません. The meaning stays the same (“haven’t eaten yet”), but you adjust formality to suit your audience:

• Polite: まだケーキを食べていません。
• Plain: まだケーキを食べていない。