1.No mountain in Viet Nam is as high as Fansipan
->Fansipan is the highest in Viet Nam
2.The MeKong river is longer than the red river
->The Red river is shorter than The MeKong river
3.It is not good to stay up so late to listen to music
->You shouldn't stay up so late to listen to music.
4.How many times a week do you go to your painting club?
->How often do you go to your paining club?
5.Nobody is older than my grandfather in my family
->My grandfather is the oldest in my family
6.It is essential that you do your homework before going to class
->You must necessary that you do your homework before going to class