Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
thanh do » thanh de, thanh pho, thanh hoa
vu khach » vu khanh, vu khac, vay khach
va thanh » gia thanh, ban thanh, va tinh
su sach » so sach, vu sach
va cao » va cac, va co, va dao
do cau » dao cau, bo cau, co cau
ve cao » ve bao, ve cac, ve co
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu khach)) ky nang x hoi. hieu ((ve cao) OR (va cao)) duc va thanh do cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu khach)) ky nang x hoi. hieu ((ve cao) OR (va cao)) duc va thanh do cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu khach)) ky nang x hoi. hieu ((ve cao) OR (va cao)) duc va thanh do cau tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu khach)) ky nang x hoi. hieu ((ve cao) OR (va cao)) duc va thanh do cau tren*.