Perhaps you should try some spelling variations:
hoat viet » hoa viet, hoai viet, khoan viet
thanh voi » thanh loi, thanh moi, hanh voi
voi hoat » toi hoat, doi hoat, vo hoat
kho tang » cao tang
truc va » thuc vat, trung va
ky tang » ky nang, ky dang, ky trong
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
su sai » su tai, su hai, su dai
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sai ((ky tang) OR (kho tang)) xa hoi. hieu ve cam ((thuc va) or (truc va)) thanh voi hoat viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sai ((ky tang) OR (kho tang)) xa hoi. hieu ve cam ((thuc va) OR (truc va)) thanh voi hoat viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sai ((ky tang) OR (kho tang)) xa hoi. hieu ve cam ((thuc va) or (truc va)) thanh voi hoat viet".
• Adding a wildcard symbol may retrieve word variants: su sai ((ky tang) OR (kho tang)) xa hoi. hieu ve cam ((thuc va) or (truc va)) thanh voi hoat viet*.