Perhaps you should try some spelling variations:
chau tinh » cuu tinh, ha tinh, cua tinh
nang cong » nang song, dang cong, bang cong
doi chau » doi chieu, gioi chau, hoi chu
cong tac » cong ty
tac nang » tac vang, tai nang, tap nang
tan toan » tan tran, tap toan, van toan
bai toan » bai tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi chau tinh - thanh cong tac nang cong ((tan toan) or (bai toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chau tinh - thanh cong tac nang cong ((tan toan) OR (bai toan)) tap.
• Adding a wildcard symbol may retrieve word variants: doi chau tinh - thanh cong tac nang cong ((tan toan) or (bai toan)) tap*.