watasi ha hurui sumaho wo kaikaemasu.

I will replace my old smartphone.

Breakdown of watasi ha hurui sumaho wo kaikaemasu.

• は: topic particle
• 私わたし: I
• を: direct object particle
• スマホ: smartphone
• 古ふるい: old
• 買かい替かえる: to replace

Questions & Answers about watasi ha hurui sumaho wo kaikaemasu.

What does 買い替えます mean exactly, and how is it different from just 買います?

買い替えます is the polite non-past form of the verb 買い替える, which literally means “to buy and replace (something old with something new).” Key points:

• 買います simply means “to buy.”
• 買い替えます implies you already have an old item and you’re replacing it by purchasing a new one.

Why is 古い placed directly before スマホ, and why isn’t there a particle like の between them?

In Japanese, い-adjectives like 古い (“old”) directly modify nouns without any additional particle. Structure:

• 古い スマホ = “old smartphone”
  No の is needed because 古い is already an adjective, not a noun.

Why do we use the particle を after スマホ, instead of が or は?

The particle を marks the direct object—the thing being acted upon. Here, スマホ is what you’re “buying and replacing.” If you used が, it would mark the subject, which doesn’t fit this verb. は could mark a topic but wouldn’t show that you’re directly replacing the smartphone.

What role does は play after 私? Could we use が instead?

は is the topic marker. It tells the listener “I’m going to talk about myself.”

• 私 は: “As for me…”
  Using が (私 が) would mark “I” as the grammatical subject, but は is more natural here since you’re making a statement about your own action.

Can you omit 私 は and just say 古い スマホ を 買い替えます?

Yes. Japanese often drops the topic/pronoun when context is clear. If it’s obvious you’re talking about yourself, 古い スマホ を 買い替えます is perfectly natural.

Is there any nuance between 買い替える and 買い直す?

They’re similar but have slight differences:

• 買い替える focuses on replacing an old item with a new one (planned upgrade).
• 買い直す literally means “buy again,” often after returning or because the first purchase was wrong/unsatisfactory.

Why is 買い替えます written with kanji and kana mixed? Could you write it all in kana?

Japanese verbs often use kanji for the root and kana for the inflection/compounding part:

• 買 (kanji for “buy”)
• い替え (kana + kanji for “replace”)
• ます (polite ending in kana)
  You can write it all in kana (かいかえます), but mixing kanji and kana is standard for readability.