Question

3) de resposta curtas na forma afirmativas e negativa .
a) are air plane slow?
b) is her boise new?
c)is this table cleam ?
d) are these books espensiver?

Answer 1

a)Yes,They are or They're. a)No, They aren't or are not.  
b)Yes, it is or it's.  b)No, it isn't or itsn't
c)Yes, it is or it's.  c)No, it's not or it isn't
d)Yes, These are.  d)No, These aren't

Correção da primeira Questão.a)Is AIRPLANE slow? or Are AIRPLANES slow?
O is é usado nos pronomes HE, SHE, IT. Ele, Ela, Ele (animal ou objeto)
O are é usado nos pronomes You(você ou vocês), we, They. No caso de they significa eles. "Os aviões", "ELES", então AIRPLANE está no plural de They. e AIRPLANE está no singular de it. E separado se não me engano, quer dizer plano de vôo "AIR PLANE" e junto é Avião "AIRPLANE".

Answer 2

a) Yes, They're or No, Thet aren't 
b)No, her isn't  or  Yes, her isn't
c) Yes,it is or No, it isn't
d) No, They aren't or Yes, They are