Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh hai » thanh hai, nhanh hai, hang hai
dai hai » dai han, dai hoi, dai tai
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cua tre » cuu tre, cua triet, dua tren
su hai » su tai
hai ky » thai ky, hoi ky, hai ly
ve cac » va cac, vien cac
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su hai ky nang ((dai hoc) or (dai hai)). hieu ve cac nuoc va hanh hai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su hai ky nang ((dai hoc) OR (dai hai)). hieu ve cac nuoc va hanh hai ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: su hai ky nang ((dai hoc) or (dai hai)). hieu ve cac nuoc va hanh hai ((cua tre) or (cua te))*.