Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
chat huu » pham huu
chat xuc » cam xuc, chao xu, chat cua
cua tre » cua te, cuu tre, cua triet
sai kho » tai khoa, dai khoa, mai khoa
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
dai kho » dai khoa, dai tho, dai ho
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sai kho) or (dai kho)) tang ma hoa. hieu va ((chat xuc) OR (chat huu)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sai kho) OR (dai kho)) tang ma hoa. hieu va ((chat xuc) OR (chat huu)) van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sai kho) or (dai kho)) tang ma hoa. hieu va ((chat xuc) OR (chat huu)) van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sai kho) or (dai kho)) tang ma hoa. hieu va ((chat xuc) OR (chat huu)) van hanh vi cua tre*.