Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » thien van, lieu va, hieu ve
cau tren » cu tren, ca tren, cau treo
dau tren » dau tien, dat tren, dau tieng
hoc cac » hoc cao
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
cau duc » cao duc, cau luc, chu duc
va dinh » van dinh, va kinh, va tinh
dinh vi » dinh ve, dinh viet, dinh tri

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc cac ky nang mai hoi. ((hieu van) or (hieu va)) cau duc va dinh vi ((cau tren) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc cac ky nang mai hoi. ((hieu van) OR (hieu va)) cau duc va dinh vi ((cau tren) OR (dau tren)).
• Adding a wildcard symbol may retrieve word variants: hoc cac ky nang mai hoi. ((hieu van) or (hieu va)) cau duc va dinh vi ((cau tren) or (dau tren))*.