Perhaps you should try some spelling variations:
chat duc » chat xuc, chat doc, chet duoc
khoa hoi » khoan hoi, khoa hoc, khoa doi
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
ky dang » ky nang, ky danh
hoa hoi » hoa hoc, hoa doi, hoc hoi
va chat » van chat, va phat, cao chat
vi cua » vai cua, di cua
su sac » su sach, su cac
su xac » pu xac, su 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 dang ((hoa hoi) OR (khoa hoi)). hieu va chat duc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sac) OR (su xac)) ky dang ((hoa hoi) OR (khoa hoi)). hieu va chat duc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sac) or (su xac)) ky dang ((hoa hoi) OR (khoa hoi)). hieu va chat duc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sac) or (su xac)) ky dang ((hoa hoi) OR (khoa hoi)). hieu va chat duc va hanh vi cua tre*.