Before starting the exercise for explanatory 「のだ」「のです」, please clarify any doubts you may have about the grammatical rules by referring to your grammar guidebook or dictionary. The Instantaneous Composition Method requires you to compose sentences with the target sentence pattern(s) over and over in order to use them almost effortlessly. You should already have the necessary knowledge.
Instantaneous Composition Exercise for Explanatory 「のだ」「のです」
This is not a translation exercise. This is the Instantaneous Composition Exercise. As if a reflexive action, try to create an equivalent Japanese sentence shortly after reading an English script. Try not to think for more than three seconds.
(I) didn’t study. (Explanatory) (It) was difficult.
勉強しませんでした。 難しかったんです。
(I) read books. (Explanatory) (I) was free.
本を読みました。暇だったんです。
(I) didn’t sleep. (Explanatory) (I) was not sleepy.
寝ませんでした。眠くなかったんです。
(I) stayed home. (Explanatory) (I) was not healthy.
家にいました。元気じゃなかったんです。
(I) cried. (Explanatory) (I) was scared.
泣きました。 怖かったんです。
Are (you) busy? => (Explanatory) Yes, (I will) leave soon.
忙しいですか？ => はい、すぐ出るんです。
Is Japanese easy? => (Explanatory) No, Kanji is difficult.
日本語は簡単ですか？ => いいえ、漢字が難しいんです。
Will (you) eat cake? => (Explanatory) Yes, (I) like (it).
ケーキを食べますか？ => はい、好きなんです。
Will (you) go to school? => (Explanatory) No, today is a day off.
学校に行きますか？ => いいえ、今日は休みの日なんです。
Will (you) buy a car? => (Explanatory) No, a car is expensive.
車を買いますか？ => いいえ、車は高いんです。
Note
のだ is the casual form and のです is the polite form. In spoken Japanese, they are often pronounced at んだ and んです respectively for the sake of simplicity in terms of pronunciation.
