The key to exercise solutions in chapter Unit 73 - The 1 for the textbook English Grammar in Use with authors Raymond Murphy from Cambridge University Press
Question
Put in the or a where necessary. (See Unit 72 for a and the if necessary.)
Answer
The sun is a star.
the same thing
Room 25 is on the second floor.
The moon goes round the earth every 27 days. /... goes round Earth ...
a very hot day ... the hottest day of the year
We had lunch in a nice restaurant by the sea.
at the cinema
eat a good breakfast
on the wrong platform
The next train ... from Platform 3
You'll find the information you need at the top of page 15.