1 . Remember to bring the compass ; if not  , we will get lost in the forest 
=> You must bring the compass ; if not , we will get lost in the forest .

2 . It is very dangerous to walk alone after 10 p. m in that park 
=> You mustn't walk alone after 10 p.m in that park .

3 . Taking a boat trip around the islands in Ha Long Bay is the most important thing of the trip. 
=> You must  take a boat trip around the islands in Ha Long Bay.

4 . It is a good idea to go to Huong Pagoda by minibus 
=> You should go to Huong Pagoda by minibus.

5 . It is very important that you arrive on time at school 
=> You must arrive on time at school.

6 . It is not good to eat too much fatty food 
=> You shouldn't  eat too much fatty food.