Perhaps you should try some spelling variations:
vu khach » vu khanh, vu khac, vay khach
thi hang » thi hanh, thi nang, thi hong
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
ve hoc » te hoc, va hoc, vi hoc
dan vi » doan vi, dan va, gan vi
nuoc » quoc, duoc, ngoc

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

• If you are trying to use Boolean operators, they must be ALL CAPS: vu khach ((ty nang) OR (thi hang)) ma hoi. hieu ve hoc nuoc va ((dan vi) OR (don vi)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu khach ((ty nang) or (thi hang)) ma hoi. hieu ve hoc nuoc va ((dan vi) OR (don vi)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: vu khach ((ty nang) or (thi hang)) ma hoi. hieu ve hoc nuoc va ((dan vi) OR (don vi)) cua tre*.