A questão quer que você transforme as frases em perguntas, todas elas apresentam o verbo "to be" então a única coisa a se fazer é por o verbo no início da frase

Explicação:

As frases ficam:

a) Is he happy?
b) Is she pretty?

c) Are you my grandson?

d) Is Mary very sad?

e) Are they old now?

f) Is the boy short?

g) Is the house big?

h) Are they students?

i) Is Mr Brown fat?

j) Are Mr and Mrs Smith my parents?

k) Is English very easy?

l) Is John very thin?

m) Are Mary and Helen young

n) Is that guy my cousin?