Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
chat hoc » chat hoa, chat thom, cho hoc
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
tu sac » tu sach, tu cac, tu san

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ((ky lang) OR (ky dang)) xa hoi. hieu va chat hoc va dan vi ((cuu tre) OR (cau theo))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ((ky lang) OR (ky dang)) xa hoi. hieu va chat hoc va dan vi ((cuu tre) or (cau theo))~".
• Adding a wildcard symbol may retrieve word variants: tu sac ((ky lang) OR (ky dang)) xa hoi. hieu va chat hoc va dan vi ((cuu tre) or (cau theo))*.