Perhaps you should try some spelling variations:
vu khach » vu khanh, vu khac, vay khach
trung va » truong va, trang va, trung ha
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
danh va » doanh va, hanh va, anh va
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
va cua » va chua, via cua, ca 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)) ky nang ma hoi. hieu van cau ((truc va) OR (trung va)) danh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu khach)) ky nang ma hoi. hieu van cau ((truc va) OR (trung va)) danh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu khach)) ky nang ma hoi. hieu van cau ((truc va) OR (trung va)) danh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu khach)) ky nang ma hoi. hieu van cau ((truc va) OR (trung va)) danh va cua tre*.