Perhaps you should try some spelling variations:
trung long » truong long, trung uong, trong long
cac trung » cac truong, dac trung, bac trung
tranh cac » trinh cac, thanh cac, tranh cai
hieu cac » hieu luc, hieu va, hieu van
long van » luong van, song van, lang van
ban tap » bai tap, ban tai, ban tay
han tap » han tai, toan tap, nhan tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu cac) or (hieu qua)) - canh tranh cac trung long van ((ban tap) or (han tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cac) OR (hieu qua)) - canh tranh cac trung long van ((ban tap) OR (han tap)).
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cac) or (hieu qua)) - canh tranh cac trung long van ((ban tap) or (han tap))*.