Мы услышали ответ сенатора.

Because услышать is the perfective verb, and it means to hear in the sense of successfully catching a sound / hearing something at a particular moment.

• услышали = heard
• слышали = were hearing / could hear / heard in a general sense

In this sentence, the idea is that we heard the senator’s answer as a completed event, so услышали fits better.

In the past tense, Russian verbs agree with the subject in gender and number.

For услышали:

• -л shows past tense
• -и shows plural

So услышали means heard with a plural subject: we heard or they heard.

Because the subject is мы (we), the plural form is required.

Ответ is the direct object of the verb услышали, so it is in the accusative case.

However, for many masculine inanimate nouns, the accusative singular looks exactly the same as the nominative singular.

So:

• nominative: ответ
• accusative: ответ

That is why the form does not visibly change.

Сенатора is the genitive singular form of сенатор.

Here it shows a relationship similar to English of the senator or the senator’s:

• ответ сенатора = the senator’s answer / the answer of the senator

So:

• сенатор = senator
• сенатора = of the senator / the senator’s

This is a very common pattern in Russian:
noun + genitive noun to show possession or association.

Normally, ответ сенатора means the senator’s answer — in other words, the answer given by the senator.

If you wanted to say the answer to the senator, Russian would usually express that differently, for example with a preposition or a different structure, depending on context.

So in this sentence, the most natural reading is the senator’s answer.

Yes. Russian often drops subject pronouns when they are clear from the verb form.

So Услышали ответ сенатора can mean We heard the senator’s answer, if the context already makes we clear.

However, мы may be included:

• for emphasis
• for contrast
• for clarity

So both are possible, but Мы услышали ответ сенатора is completely normal.

Yes. Russian word order is more flexible than English word order because case endings show the grammatical roles.

For example, these are all possible:

• Мы услышали ответ сенатора.
• Ответ сенатора мы услышали.
• Мы ответ сенатора услышали.

They all mean basically the same thing, but the focus changes.

• Мы услышали ответ сенатора = neutral
• Ответ сенатора мы услышали = emphasizes the senator’s answer
• Мы ответ сенатора услышали = can emphasize the fact that we did hear it

So word order in Russian often affects emphasis, not basic meaning.

Russian has no articles, so it does not have direct equivalents of the and a/an.

That means:

• ответ can mean an answer or the answer
• сенатора can mean of a senator or of the senator

The exact meaning is understood from context.

So Russian expresses this sentence without articles, even though English usually needs them.

Russian can sometimes use an adjective instead of a genitive noun, but here ответ сенатора is the normal and natural way to say the senator’s answer.

A derived adjective would usually sound different in meaning or style, and often less natural in everyday speech for simple possession.

So for straightforward possession or authorship, noun + genitive is the standard choice here.

The dictionary forms are:

• мы = we
• услышали → dictionary form: услышать
• ответ = answer
• сенатора → dictionary form: сенатор

This is useful because Russian words often appear in changed forms in sentences, especially verbs and nouns.

No. They are related, but they mean different things.

• слушать = to listen
• услышать = to hear

So:

• Мы слушали ответ сенатора = We listened to the senator’s answer
• Мы услышали ответ сенатора = We heard the senator’s answer

In your sentence, the meaning is about hearing, not actively listening.

It is genitive singular.

You can recognize it because:

1. the phrase ответ кого? чего? often takes the genitive
2. masculine nouns like сенатор often change -ор to -ора in the genitive singular:
   • сенатор
   • сенатора

This is a very common Russian pattern, so it is worth memorizing early.