Я испачкал рубашку соусом.

I

Breakdown of Я испачкал рубашку соусом.

• рубашка: the shirt
• соус: the sauce
• испачкать: to stain

Questions & Answers about Я испачкал рубашку соусом.

Why is the verb испачкал and not испачкать?

Испачкать is the infinitive, meaning to stain / to make dirty.

In the sentence, you need a finite verb, not an infinitive, so Russian uses the past-tense form испачкал. This form tells you:

• the action is in the past
• the subject is singular
• the speaker is masculine

If the speaker were female, it would be испачкала.
If it were we/they, it would be испачкали.

Also, in Russian past tense, the verb does not show person, so я is what tells you the subject is I.

Why is рубашку not рубашка?

Because рубашку is in the accusative case, which is the case usually used for a direct object.

Here, the shirt is the thing that got stained, so it is the direct object of испачкал.

• nominative: рубашка = shirt
• accusative: рубашку = shirt as the object of the verb

So:

• рубашка = the shirt is doing something / being talked about as the subject
• рубашку = someone did something to the shirt

Why is соусом in the instrumental case?