Perhaps you should try some spelling variations:
dang xay » dang van, van xay
cau theo » cau thi
hieu ve » hieu va, hieu van
cam duc » cam xuc, cao duc, pham duc
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
ve cam » ve cham, ve cac, va cam
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky ((nang x) or (dang xay)) hoi. hieu ve cam duc va dan vi ((cau theo) OR (cau tao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((nang x) OR (dang xay)) hoi. hieu ve cam duc va dan vi ((cau theo) OR (cau tao)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky ((nang x) or (dang xay)) hoi. hieu ve cam duc va dan vi ((cau theo) OR (cau tao))".
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((nang x) or (dang xay)) hoi. hieu ve cam duc va dan vi ((cau theo) OR (cau tao))*.