Ответ:
a
Singular
- a bag
- a country
- an identity card
- a watch
- an e-mail
- a sandwich
- a key
- an umbrella
Plural
- bags
- countries
- identity cards
- watches
- e-mails
- sandwiches
- keys
- umbrellas
b
Teacher: What's this, Tim?
Tim: It's a mobile.
Teacher: And what are those, Tim?
Tim: They're megazines.
Teacher: Give them to me.
Man: What's that?
Woman: It's a cat.
Man: Who are these boys?
Woman: They're your students. Put your glasses on!