Perhaps you should try some spelling variations:
dang tay » dang xay, dung tay, bang tay
dan tay » ban tay, dao tay, gian tay
hieu va » lieu va, hieu qua
cac hoc » cach hoc, cac hop, bac hoc
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
cua tre » cua te, cuu tre, cua triet
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 cac ky ((dang tay) OR (dan tay)) hoi. hieu va cac hoc ((va hanh) or (va danh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky ((dang tay) OR (dan tay)) hoi. hieu va cac hoc ((va hanh) OR (va danh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky ((dang tay) OR (dan tay)) hoi. hieu va cac hoc ((va hanh) or (va danh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu cac ky ((dang tay) OR (dan tay)) hoi. hieu va cac hoc ((va hanh) or (va danh)) vi cua tre*.