Perhaps you should try some spelling variations:
mach hoc » cach hoc, dich hoc, anh hoc
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
su mach » su sach
cau hoa » cau hoi
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
hoc da » hoc dan, hoc dai, hoc dat
hoi ca » hoi cua, hoi cac, hoi cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: su mach hoc tap, nghien ((cuu khoa) or (cau hoa)) hoc da khoa hoc mai hoi ca nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su mach hoc tap, nghien ((cuu khoa) OR (cau hoa)) hoc da khoa hoc mai hoi ca nhan dan.
• Adding a wildcard symbol may retrieve word variants: su mach hoc tap, nghien ((cuu khoa) or (cau hoa)) hoc da khoa hoc mai hoi ca nhan dan*.