Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
so sinh » so sanh, so tinh, hoa sinh
tang ma » mang may, tang van
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao
y tang » ky tang, 6 tang, 7 tang
vi cua » vai cua, di cua
ve cam » ve cham, ve cac, ve cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sinh) OR (cho sinh)) y tang ma hoi. hieu ((ve cam) or (va cam)) truc va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sinh) OR (cho sinh)) y tang ma hoi. hieu ((ve cam) OR (va cam)) truc va hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sinh) OR (cho sinh)) y tang ma hoi. hieu ((ve cam) or (va cam)) truc va hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: ((so sinh) OR (cho sinh)) y tang ma hoi. hieu ((ve cam) or (va cam)) truc va hanh vi cua viet*.