Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
vu khach » vu khanh, vu khac, vay khach
thuc van » thuc vat, thuc dan, thuc va
su sach » so sach, vu sach
va cham » va chat, va tham
ve cham » ve chat, vu cham, ve chim
tang ma » mang may, tang van
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
y tang » ky tang, 6 tang, 7 tang
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu khach)) y tang ma hoi. hieu ((ve cham) or (va cham)) thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu khach)) y tang ma hoi. hieu ((ve cham) OR (va cham)) thuc van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu khach)) y tang ma hoi. hieu ((ve cham) or (va cham)) thuc van hanh vi cua tre*.