This lesson will teach you how to make your Japanese sentence sounds more natural using the grammar Plain form のです (Plain form no desu).
After learning Japanese for some time, you will notice that native Japanese speak differently from what you have learned so far. One of the differences is that they like to add a の (no) at the end of a sentence.
This is to make the sentence sounds more natural. Besides, the speaker used this grammar to:
Let's look at the sentence pattern of this grammar...
Plain form のですか
Plain form no desu ka
Plain form のです
Plain form no desu
Note: For な-adj/Noun -> (～
While the above sentence pattern is used in writing, it's changed to Plain form んです (Plain form n desu) when it's used in conversation because it's easier to pronounce.
There is one condition when using this Japanese sentence. In order to use it, something should be obvious on whatever you have seen or heard. Let's use some examples to explain this condition.
Let's say summer vacation in coming soon. The teacher is asking the students where they are going for their holidays. The teacher probably says...
As the students are still in the classroom wearing their school uniform, the teacher has no idea where they are going for their holidays. Therefore she can only ask with a question like "どこへ行きますか" (doko e ikimasu ka).
Let's say now that you see your neighbour is waiting for taxi with his travel suitcase beside him and he is also carrying a camera. It's obvious that your neighbour is going for travel. You want to make sure that he is really going for travel. In this case you can ask him...
As opposed to the first example, it's obvious that your neighbour is going for travel. And you want to confirm that. In this case you can use Plain form no desu in the Japanese sentence.
Assume you are inside the office. If you want to ask someone if it's raining outside, how do you ask? You will probably ask...
However, if you see your colleague carrying a wet umbrella into the office, you should use Plain form no desu.
It's not a mistake to say "雨が降っていますか。" (ame ga futte imasu ka) for the second case. But native Japanese use Plain form no desu for something obvious, as it's more natural.
Let's see another example to make sure what situation is considered as obvious.
Suppose today you notice that your colleague who used to maintain long hair suddenly appeared in front of you with short hair. You are surprised and ask her...
You have seen your colleague with long hair until yesterday. It's obvious that she had cut her hair. Therefore it's natural to use Plain form no desu in the Japanese sentence here.
However, if you are talking to your colleague through phone without knowing her new hair style, you will ask her...
For sentences ended with Noun or Na-adjective, instead of ending だ (da), change it to な (na). For example, if you see a tourist carrying a Japanese passport in his hand, it's obvious that he is a Japanese. So you can ask him the following to confirm...
However if it's not obvious (he is not carrying a Japanese passport), you can only ask him...
In summary, you can only use this Japanese sentence when something is obvious, either you have seen or heard about it. It also shows your curiosity and you are seeking for an explanation.
And since you are using this Japanese sentence to ask questions, it always goes with the question word どうして (doushite - why). The answer to this type of questions is always "Plain form からです" (Plain form kara desu), as shown in the following sentence patterns...
どうして Plain form のですか
doushite Plain form no desu ka
Plain form からです
Plain form kara desu
As から (kara) also has the meaning of "reason", it always paired with どうして (doushite) question. For example...
Answer: 頭が痛かった から です。
atama ga itakatta kara desu
Meaning: Because I had a headache.
Answer: 今日は妻の誕生日だ から です。
kyou wa tsuma no tanjoubi da kara desu
Meaning: Because today is my wife's birthday.
Don't forget that the Japanese grammar Plain form no desu is usually used in writing. However during a conversation, の (no) is changed to ん (n).
Lesson 20: Japanese Grammar for Cause and Reason.
Lesson 34: Particle de (で) for Cause or Reason.
FAQ Page: How to use から (kara) in Japanese for reason.