Perhaps you should try some spelling variations:
hang hai » hoang hai, hang tai, thanh hai
nang dai » nang dau, nang tai, lang dai
hanh hai » thanh hai, nhanh hai, hanh tai
cua tre » cua te, cuu tre, cua triet
dai hai » dai han, dai hoi, dai tai
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
su sac » su sach, su cac
luc va » duc va, tuc va, loc va
su xac » pu xac, su cac
ve cac » va cac, vien cac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sac) or (su xac)) ky nang dai hai. hieu ve cac luc va ((hanh hai) OR (hang hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sac) OR (su xac)) ky nang dai hai. hieu ve cac luc va ((hanh hai) OR (hang hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sac) or (su xac)) ky nang dai hai. hieu ve cac luc va ((hanh hai) OR (hang hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sac) or (su xac)) ky nang dai hai. hieu ve cac luc va ((hanh hai) OR (hang hai)) cua tre*.