Perhaps you should try some spelling variations:
ban hang » ngan hang
cuu tre » cua tre, cau tren, cau treo
va danh » va dinh, va dan, va hanh
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
cai ky » cao ky, cac ky, cam ky
di cuu » di cau, di cua, dinh cuu
tu cai » tu cac, tu can, tu bai
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cai ky nang ((x hoi) OR (o hoi)). hieu ve cham soc ((ban hang) or (va danh)) di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cai ky nang ((x hoi) OR (o hoi)). hieu ve cham soc ((ban hang) OR (va danh)) di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cai ky nang ((x hoi) OR (o hoi)). hieu ve cham soc ((ban hang) or (va danh)) di cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu cai ky nang ((x hoi) OR (o hoi)). hieu ve cham soc ((ban hang) or (va danh)) di cuu tre*.