이에요 or 예요

Korean says "A is B" by attaching 이에요 or 예요 directly to the noun, with no space. The choice depends only on the noun's last sound:

• After a final consonant (batchim): 이에요, as in 학생이에요 (I'm a student) or 일요일이에요 (it's Sunday).
• After a vowel: 예요, as in 커피예요 (it's coffee) or 의사예요 (he's a doctor).

The question words 뭐, 어디, 얼마 and 누구 all end in a vowel, so it is always 뭐예요?, 어디예요?, 얼마예요? and 누구예요?. The same goes for 거 in 제 거예요 (it's mine). To ask a question, keep the same form and raise your voice: 학생이에요? The negative is always 아니에요, never 아니예요: 학생이 아니에요 (I'm not a student).