Perhaps you should try some spelling variations:
khoa hoi » khoan hoi, khoa doi, khoa noi
khoa hoc » hoa hoc
chat hoc » chat hoa, chat thom, cho hoc
hanh tai » thanh tai, hang tai, han tai
ky lang » ky nang, ky dang, ky tang
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
va hanh » van hanh, va thanh, ban hanh
su xac » pu xac, su cac
xac ky » cac ky, sac ky, bac ky
ha hoi » hoa hoi, ha noi, xa hoi
tai va » thai va, mai va, tri va
thiet* » thieu*

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

• Performing a fuzzy search may retrieve terms with similar spellings: su xac ky lang ((ha hoi) or (((khoa hoi) OR (khoa hoc)))). hieu va chat hoc va hanh tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su xac ky lang ((ha hoi) OR (((khoa hoi) OR (khoa hoc)))). hieu va chat hoc va hanh tai va thiet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su xac ky lang ((ha hoi) or (((khoa hoi) OR (khoa hoc)))). hieu va chat hoc va hanh tai va thiet*".