Perhaps you should try some spelling variations:
lam truoc » lam thuoc, nam truoc, lam truong
hieu van » hieu va, thien van, lieu va
truoc va » truc va, thuoc va, truong va
dau tren » dau tien, dat tren, dau tieng
nang ma » tang ma, sang ma, nang cao
van lam » van nam
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
tu van » tu va
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu van ky ((mang may) or (nang ma)) hoi. hieu van lam truoc va hanh va dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu van ky ((mang may) OR (nang ma)) hoi. hieu van lam truoc va hanh va dau tren.
• Adding a wildcard symbol may retrieve word variants: tu van ky ((mang may) or (nang ma)) hoi. hieu van lam truoc va hanh va dau tren*.