Substitute : Desu as a substitute for a verb

Examples
1. A : Nanji ni okimasu ka.
"What time do you get up?"
B : Rokuji desu.
"I get up at six o'clock."
2. A : Doko e ikimasu ka.
"Where are you going?"
B : Kyooto desu.
"I'm going to Kyoto."
2. A : Kaarin san wa doko ni imasu ka.
"Where is Karin san?"
B : Shokudoo desu.
"She's in the cafeteria."
In each of the examples above, desu serves as a substitute for the verb used in the previous sentence : okimasu "get up," ikimasu"go" or imasu "be." Desu is used to avoid repeating the verb mentioned previously. Desu cannot be used alone. It follows a noun. The Group 1 particles, ga, o, e and ni, are omitted before desu,
while kara, made, etc. are kept.

Examples
1. A : Arisu san wa doko ni imasu ka.
"Where's Alice san?"
B : Shokudoo desu.
"She's in the cafeteria."
2. A : Kaarin san wa doko desu ka."
"Where is Karin san?"
B : Seekyoo desu.
"She's in the Co]op."
3. A : Ruin san wa doko kara kimashita ka.
"Where did Mr. Lwin come from?"
B : Biruma kara desu.
"He's from Burma."
Alice : Ruin san wa nani o tabemasu ka.
"What will you eat?"
Lwin : Watashi wa sakana desu.
"I'll eat fish."
Alice : Kaarin san wa.
"How about you, Karin san?"
Kalin : Niku desu.
"I'll eat meat."

The sentence "Watashi wa sakana desu." may sound strange. But this desu does not mean the equality of two nouns. You should get used to this desu as soon as possible.
Desu can replace not only the imperfective form of a verb but also the perfective
form of a verb.

Examples
1. A : Kinoo doko e ikimashita ka.
"Where did you go yesterday?"
B : Tookyoo desu.
"I went to Tokyo."
2. A : Depaato de nani o kaimashita ka.
"What did you buy at the department store?"
B : Teepurekoodaa desu.
"I bought a tape recorder."