Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty xang, ly nang
ty hang » ly hang, ty xang, thi hang
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
luc va » tuc va, loc va
vi cau » va cau, ve cau, di cau

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 sach ((ty nang) OR (ty hang)) xa hoi. hieu ve cac ((luc va) OR (duc va)) hanh vi cau tren~.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ty hang)) xa hoi. hieu ve cac ((luc va) or (duc va)) hanh vi cau tren*.