Perhaps you should try some spelling variations:
duong vanh » duong van, duong xanh, duong anh
duong manh » duong van
hieu lang » chieu sang, hieu quang, nhieu tang
canh manh » lanh manh, canh tranh, cach mang
cua nhung » va nhung
hoc hieu » hoc thieu, hoc hien, doc hieu
manh cua » doanh cua, ban cua
toan cau » toan cao, toan ban, toan tap

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: hoc hieu lang - canh manh cua nhung ((duong vanh) OR (duong manh)) toan cau~.
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - canh manh cua nhung ((duong vanh) or (duong manh)) toan cau*.