Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
nang cai » nang cao, nang tai, nang cap
cham duc » cham soc, pham duy, phan duc
su sach » so sach
tai duc » tai cuc, mai duc, tai du
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
cai hoi » cau hoi, dai hoi, cai hoa
vu sach » vu bach, vu khach
duc tre » duoc tren, duc tien

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 sach)) ky nang cai hoi. hieu va ((cham duc) OR (pham duc)) va hanh tai duc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky nang cai hoi. hieu va ((cham duc) OR (pham duc)) va hanh tai duc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ky nang cai hoi. hieu va ((cham duc) OR (pham duc)) va hanh tai duc tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ky nang cai hoi. hieu va ((cham duc) OR (pham duc)) va hanh tai duc tre*.