In my opinion, you should not eat lukewarm food so often

1.In my opinion, you should not eat lukewarm food so often.
→ I don't think
2. It isn't a good idea for you to put so much salt in the soup.
→ You.. 
3. What impressed me most was the terraced rice fields in Mù Cang Chải District. (FOUND)
→ It was