Странно, что он так и не ответил.

Странно is the short-form neuter adverb/predicative form meaning it is strange.

In this sentence, Russian is not describing a noun as strange. It is making a general comment about the whole situation:

• Странно, что он так и не ответил. = It’s strange that he never replied.

This is very common in Russian with words like:

• интересно = it’s interesting
• жаль = it’s a pity
• важно = it’s important
• непонятно = it’s unclear

So странно here functions like English it’s strange, not like an adjective modifying a noun.

Russian often does not use a dummy subject like English it.

English says:

• It’s strange that...

Russian simply says:

• Странно, что...

That is completely normal. Russian often leaves out words that English requires for grammar but that do not carry real meaning.

So:

• Странно = It’s strange
• not literally strange

Because что introduces a subordinate clause.

The sentence has two parts:

• Странно = main statement
• что он так и не ответил = subordinate clause explaining what is strange

Russian normally puts a comma before что in this kind of structure:

• Я знаю, что он дома.
• Жаль, что ты ушёл.
• Странно, что он так и не ответил.

So the comma is required.

Here что means that.

So:

• Странно, что он так и не ответил.
• It’s strange that he never replied.

This is one of the most common uses of что: introducing a clause after verbs or expressions like:

• я думаю, что... = I think that...
• ясно, что... = it’s clear that...
• жаль, что... = it’s a pity that...

Так и не is a very common Russian expression that adds the idea of:

• in the end didn’t
• never did, despite expectation
• still didn’t

So:

• Он не ответил. = He didn’t reply.
• Он так и не ответил. = He never replied / He still never replied / He ended up not replying.

This phrase often suggests that a reply was expected, perhaps even waited for, but it never happened.

Other examples:

• Я так и не понял. = I never did understand.
• Она так и не пришла. = She never came after all.
• Мы так и не встретились. = We never ended up meeting.

So in your sentence, так и не makes the lack of reply feel more noticeable or disappointing.

Because the sentence is talking about a completed situation in the past: the person did not reply.

• ответил = past masculine singular of ответить

Since the subject is он, the past tense ends in -л:

• он ответил
• она ответила
• оно ответило
• они ответили

Even though English might sometimes say hasn’t replied, Russian often uses the past tense in this kind of context depending on the situation.

This is a verb aspect question.

• ответить = perfective
• отвечать = imperfective

In this sentence, ответил is used because it refers to a single completed act of replying. The point is whether the reply happened at all.

• Он так и не ответил. = He never replied.
  The expected completed action did not occur.

If you used отвечал, it would usually suggest a repeated or ongoing action, or focus on the process rather than the result. That is less natural here.

So Russian uses the perfective because the idea is:

• there was supposed to be one actual reply
• that reply never happened

Он means he, and it is the subject of ответил.

Russian can sometimes omit subject pronouns when the meaning is clear from context. So in some situations you might hear:

• Странно, что так и не ответил.

But including он is perfectly normal and often clearer, especially when:

• you want to identify who you mean
• there could be more than one possible person
• you want a more neutral, complete sentence

So yes, Russian could omit it in the right context, but here он is natural.

The word order is natural, but Russian is fairly flexible.

The standard version:

• Странно, что он так и не ответил.

This sounds neutral and natural.

You could also hear variations, but they may change emphasis:

• Странно, что так и не ответил он.
  This puts more emphasis on he.
• Он так и не ответил. Странно.
  This separates the comment for effect.

So the given order is the most straightforward one for ordinary speech and writing.

Not by itself in the usual sense. In так и не, the word так is part of a fixed expression.

So you should learn так и не as a unit, not as:

• так = so
• и = and
• не = not

That literal breakdown is not very helpful here.

As a whole, так и не means something like:

• never did
• still didn’t
• in the end didn’t

So in this sentence, it is better to understand:

• так и не ответил = never replied / still didn’t reply

Yes, that is a very reasonable translation in many contexts.

Because of так и не, the Russian sentence often carries the idea that:

• a reply was expected
• time passed
• the reply never came

Depending on context, good English translations could include:

• It’s strange that he never replied.
• It’s strange that he still hasn’t replied.
• It’s odd that he never did reply.
• It’s strange that he ended up not replying at all.

The best English version depends on the surrounding situation, but still hasn’t replied often captures the nuance well.

It is completely normal in both everyday speech and writing.

• Странно is neutral.
• что он так и не ответил is also neutral and very common.

So this sentence is not especially formal, literary, or slangy. It is just standard Russian.

You could say it in conversation, write it in a message, or use it in more formal writing as well.