Breakdown of sumaho de douga wo miruno ha benri desu.
はha
topic particle
ですdesu
to be
をwo
direct object particle
見るmiru
to watch
でde
means particle
動画douga
video
スマホsumaho
smartphone
〜の〜no
verb nominalizer
便利benri
convenient
Elon.io is an online learning platform
We have hundreds of Japanese lessons and thousands of exercises.

Questions & Answers about sumaho de douga wo miruno ha benri desu.
What does で after スマホ mean?
In this sentence, で marks the means or instrument you use to do something. So スマホで means “with a smartphone” or “on your smartphone” (i.e., using a smartphone).
What is the role of を in 動画を?
The particle を marks the direct object of a transitive verb. Here 動画 (video) is what you are watching, so 動画を indicates “video” is the object of 見る (to watch).”
Why is there の after 見る? Can't we drop it and just say スマホで動画を見るは便利です?
The の here is a nominalizer: it turns the verb phrase スマホで動画を見る into a noun-like phrase. You need it because you can’t attach the topic marker は directly to a verb; you must first nominalize the clause. Without の, the sentence would be ungrammatical.
What’s the difference between using の and こと for nominalization? Could I say スマホで動画を見ることは便利です?
Both の and こと can nominalize verbs. Generally, の feels more casual and personal, while こと is slightly more formal or abstract. Yes, you could say スマホで動画を見ることは便利です, but it sounds more formal or written than 見るのは便利です.
Why is は placed after 見るの instead of after スマホ or 動画?
The topic of the sentence is the entire activity “watching videos on a smartphone,” not just “smartphone” or “video.” To mark this whole action as the topic, you nominalize it with の and then attach は. If you put は after スマホ, you’d change the focus to the smartphone itself.
The sentence ends with 便利です. Could I say 便利だ or drop です entirely?
Since 便利 is a な-adjective, you can use です (polite) or だ (plain):
- Polite: 便利です
- Plain: 便利だ
In casual speech, you might even hear 便利 without だ:
スマホで動画を見るのは便利.
Why is 動画を placed before 見る? Could I say 見る動画をスマホで?
Japanese follows a Subject-Object-Verb (SOV) order, so the object 動画を comes before the verb 見る. Saying 見る動画をスマホで is ungrammatical in this context. (However, you can form a relative clause like スマホで見る動画は…, which changes the meaning to “the videos that you watch on a smartphone.”)