Perhaps you should try some spelling variations:
toc sac » toc sach, toc san, hoc sach
dan tai » van tai, dan thi, han tai
dan vai » dan va, dan vat, den vai
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
nam tu » nam thu, nam thuc
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam tu va ((dan vai) OR (dan tai)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ((ky lang) OR (ky dang)) xa hoi. hieu va nam tu va ((dan vai) OR (dan tai)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam tu va ((dan vai) OR (dan tai)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam tu va ((dan vai) OR (dan tai)) cuu tre*.