Find mistakes and correct them

Tìm lỗi sai và sửa lỗi:
1. you shouldn't waste your time to surf the web so frequently
2. there is fewer rainfall in Viet Nam this year than the previous one
3. he studied very hard, so he passed the exam easy
4. they had all the carpets cleaned, hadn't they
5. i went to the library to get as many information as i could