gomi wo suteta ato, yuka no hokori mo hukimasita.

Because あと means after, and when it follows a verb, that verb usually appears in the plain past form to mean after doing X.

So:

• ごみを捨てたあと = after throwing away the trash

This pattern is very common:

• 食べたあと = after eating
• 帰ったあと = after going home
• 勉強したあと = after studying

Using 捨てるあと would sound unnatural here.

Here, あと means after in a time-sequence sense.

So the sentence is showing the order of actions:

1. threw away the trash
2. wiped the dust on the floor

In Japanese, Vた + あとで / あと is a very common way to say after doing V.

• ごみを捨てたあと、床のほこりも拭きました。
• After throwing away the trash, I also wiped the dust off the floor.

In this sentence, あと works almost like a time marker connecting the first action to the second.

The particle を marks the direct object of the verb.

Here:

• ごみ = trash / garbage
• 捨てた = threw away

So:

• ごみを捨てた = threw away the trash

It tells you what was thrown away.

The particle の links two nouns together. It often works like of, or it shows that one noun belongs to or is associated with another.

So:

• 床 = floor
• ほこり = dust
• 床のほこり = the floor’s dust / dust on the floor

In natural English, we would usually say the dust on the floor.

This use of の is extremely common:

• 机の上 = the top of the desk / on the desk
• 日本の車 = Japanese cars / cars from Japan
• 部屋のドア = the room’s door / the door of the room

も means also or too.

It shows that wiping the dust was an additional action.

So the sentence implies something like:

• I threw away the trash, and also wiped the dust on the floor.

Without も, the sentence would simply state that the speaker wiped the dust. With も, it emphasizes that this happened in addition to something else.

Compare:

• 床のほこりを拭きました。 = I wiped the dust on the floor.
• 床のほこりも拭きました。 = I also wiped the dust on the floor.

Yes, ほこり is the object of 拭きました, but も can replace を.

So:

• 床のほこりを拭きました = wiped the dust on the floor
• 床のほこりも拭きました = also wiped the dust on the floor

In other words, も takes over the particle slot here.

This happens a lot in Japanese:

• 水を飲みました → drank water
• 水も飲みました → also drank water

So in this sentence, も both marks the noun phrase and adds the meaning also.

They are:

• 捨てた → dictionary form: 捨てる = to throw away
• 拭きました → dictionary form: 拭く = to wipe

Here’s how they changed:

• 捨てる → 捨てた
  plain past form
• 拭く → 拭きました
  polite past form

So the sentence mixes:

• a plain past form before あと
• a polite past form at the end of the sentence

That is completely normal.

It may look mixed at first, but this is normal.

The final verb of the sentence, 拭きました, determines the overall politeness level. Since it is polite, the whole sentence sounds polite.

The earlier verb, 捨てた, is inside the grammar pattern Vたあと, so it must be in that form. It is not acting as the main sentence-ending verb.

So this is standard Japanese:

• ごみを捨てたあと、床のほこりも拭きました。

You could think of it like:

• After throwing away the trash, I also wiped the dust on the floor.

The after throwing away part is just a time clause, so it does not need to match the politeness of the final verb.

It is read ふきました.

So the full sentence is read:

ごみ を すてた あと、ゆか の ほこり も ふきました。

Useful readings here:

• 捨てる = すてる
• 床 = ゆか
• 拭く = ふく

Literally, it says wiped the dust on the floor.

Japanese often focuses on what was removed or dealt with, rather than phrasing things exactly the way English does.

So:

• 床のほこりを拭きました
• literally: wiped the floor’s dust
• natural English: wiped the floor / wiped up the dust on the floor

In context, it means the speaker cleaned dust from the floor.

Yes, the subject is omitted.

Japanese very often leaves out subjects when they are understood from context. So the sentence does not explicitly say I, she, we, etc.

Depending on context, it could mean:

• I threw away the trash and also wiped the dust on the floor.
• He/She threw away the trash and also wiped the dust on the floor.

In many learning materials, the most natural default translation is I.

Yes. あと and あとで are both possible in many cases here.

• ごみを捨てたあと、床のほこりも拭きました。
• ごみを捨てたあとで、床のほこりも拭きました。

Both mean essentially the same thing: after throwing away the trash, I also wiped the dust on the floor.

Very generally:

• あと can sound a little more compact
• あとで can sound a little more explicitly adverbial

But in everyday use, both are common.

ほこり means dust.

It usually refers to fine dry dust, not general dirt or mud.

So:

• 床のほこり = dust on the floor

If you wanted to talk about dirt more generally, Japanese might use other words depending on the situation, such as 汚れ（よごれ） for stains, grime, or dirtiness.

The comma helps separate the after doing X part from the main action.

So the structure is:

• ごみを捨てたあと、 = after throwing away the trash,
• 床のほこりも拭きました。 = I also wiped the dust on the floor.

Japanese commas are often used more flexibly than English commas, but here it makes the sentence easier to read by marking the pause between the time clause and the main clause.