в предложении должна быть сравнительная степень, плиз помогите

1 My room is not tidier than my sister`s
2 Sirius is the brightest star in the sky at night
3 This is not the most difficult question you have to answer.
4 Life now is easier than a hundred years ago
5 Is Moscow bigger than London?
6 I am the youngest person in my family.
7 Everest is the highest mountain in the world.
8 The weather today is much worse than it was a month ago.