Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
vu khach » vu khanh, vu khac, vay khach
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
van cau » van dau, van hau, van chat
ma cua » manh cua, mang cua
ca cua » co cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu khach ((ky lang) OR (ky dang)) xa hoi. hieu van cau thuc vat thanh ((ma cua) or (ca cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu khach ((ky lang) OR (ky dang)) xa hoi. hieu van cau thuc vat thanh ((ma cua) OR (ca cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu khach ((ky lang) OR (ky dang)) xa hoi. hieu van cau thuc vat thanh ((ma cua) or (ca cua)) tre".
• Adding a wildcard symbol may retrieve word variants: vu khach ((ky lang) OR (ky dang)) xa hoi. hieu van cau thuc vat thanh ((ma cua) or (ca cua)) tre*.