Perhaps you should try some spelling variations:
nhanh chong » khanh phong
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
mach hoc » cach hoc, dich hoc, anh hoc
cong hoc » dong hoc, cong hoa, cong coc
bai toan » bai tap
toan ban » van ban
tu mach » tu cach, tu manh, tu hach
hoi bai » hoc bai, hoi tai, khoi bay
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu mach hoc tap, nghien thu cong hoc ((thanh cong) or (nhanh chong)) hoc ma hoi bai toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu mach hoc tap, nghien thu cong hoc ((thanh cong) OR (nhanh chong)) hoc ma hoi bai toan ban.
• Adding a wildcard symbol may retrieve word variants: tu mach hoc tap, nghien thu cong hoc ((thanh cong) or (nhanh chong)) hoc ma hoi bai toan ban*.