Perhaps you should try some spelling variations:
hieu va » lieu va, hieu qua
hoc can » hoc dan, hoc cao, hoc cac
cuu tre » cua tre, cau tren, cau treo
tao hoi » tao khoi, tao boi, thao hoc
tay hoi » tay ho, tay thai
ky sang » ky nang, ky dang, ky tang
sac ky » cac ky, sai ky
vi cuu » vi luu, vinh cuu
te sac » te sach, te cac, te 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: te sac ky sang ((tao hoi) OR (tay hoi)). hieu va cac ((duc va) OR (hoc can)) hanh vi cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky sang ((tao hoi) OR (tay hoi)). hieu va cac ((duc va) or (hoc can)) hanh vi cuu tre~".
• Adding a wildcard symbol may retrieve word variants: te sac ky sang ((tao hoi) OR (tay hoi)). hieu va cac ((duc va) or (hoc can)) hanh vi cuu tre*.