Noun1 は Noun2 です : Noun1 is Noun2

(wa) is the particle which indicates the subject or the topic of the sentence

です(desu) is a verb which means“to be”or “to equal”. It shows the identity or the state of things and people.

 

Subjects actually tend to be omitted in the conversation whenever it is clear to the listener what or who they are talking about.

 

ではありません : Noun1 is not Noun2

です(desu) is replaced with ではありません(dewa arimasen) to make a sentence in the negative form.

 

Instead of ではありません(dewa arimasen), じゃないです(ja arimasen) is used in informal speech.

 

でした : Noun1 was Noun2

です(desu) is replaced with でした (deshita) to make the past tense in the affirmative form.

 

ではありませんでした : Noun1 was not Noun2

です(desu) is replaced with ではありませんでした(dewa arimasendeshita) to make the past tense in the negative form.

 

Instead of ではありませんでした(dewa arimasen), じゃなかったです(ja nakatta desu) is used in informal speech.

 

Japanese lesson 1 with exercises in interactive PDF format is available.
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