Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
dua tren » dung tren
tu sach » thu sach, su sach, te sach
ky lang » ky dang, ky tang, tay lang
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
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: tu sach ((ky lang) or (ky nang)) mai hoi. hieu ve cac nuoc va hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky nang)) mai hoi. hieu ve cac nuoc va hanh vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky nang)) mai hoi. hieu ve cac nuoc va hanh vi ((dua tren) or (cuu tre))*.