です → だ
“I like your grit. Hustle could use some work though, now let’s solve this thing!” - Cave Johnson, Portal 2
The first casual noun sentence ender is だ. Here’s how simple it is.
To make a sentence casual, just replace です with だ.
Of course, in sentences that don’t have です in them, you wouldn’t be doing that (and you’ll learn how to do that when you learn about adjectives and verbs). When a sentence ends with a noun, though, this is all you do. Easiest way to see it is via examples, I think:
audioいぬ です
It is a dog
audioいぬ だ
It is a dog (casual)
audioねこ です
It is a cat
audioねこ だ
It is a cat (casual)
Now it’s your turn. We won’t spend a lot of time doing things like this (because I’m going to wait to have you do most of your practice in the Casual Adjectives chapter), but you should be able to convert these sentences from formal to casual pretty easily. I’m going to try to use some of the nouns you just studied (Group01) in these examples, as well as other words you’ve learned up until now.
わたし の こえ です
audioわたし の こえ だ (It is my voice)
かれ の まえ です
audioかれ の まえ だ (At his front / In front of him)
それ は わたしたち の 犬 です
audioそれ は わたしたち の 犬 だ (That is our dog)
じぶん の め です
audioじぶん の め だ (It is my own eye/s)
Make sure you practice Group01 of the nouns. You’ll be moving somewhat fast with the nouns (compared to the other lists), so it’s important that you keep up with it so you never feel behind (and can focus on learning the grammar rather than the words)!
I think you probably felt okay with formal→casual です, so let’s move on to the next one, でした.