Question

can we use preposition at with expression like 'the night'?can we use word earth without the article 'the'?the expression 'at summer'is correct or not?

Answer 1

Yes you can use the preposition  "at" while writing the word night.
But the word earth cannot be used without the article "the".And it's becoz when your talking about the word earth then your talking specifically about earth and as we know there is only one earth.so when your talking about any  specified thing the article "the" must be used....