Perhaps you should try some spelling variations:
lam truoc » lam thuoc, nam truoc, lam truong
dat tren » dat trong, dua tren
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
ve lam » va lam, de lam, se lam
va dat » va dao, va dau, va dap
tu van » tu va

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