Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
cu tren » tu tren, dua tren
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
truc va » thuc va, trung va
dao ca » dao cac, dao cao, dao cau
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
ve cam » ve cham, ve cac, va cam
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang ma hoi. hieu ve cam ((truc va) or (thuc vat)) dao ca ((dau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ma hoi. hieu ve cam ((truc va) OR (thuc vat)) dao ca ((dau tren) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ma hoi. hieu ve cam ((truc va) or (thuc vat)) dao ca ((dau tren) or (cu tren))*.