Perhaps you should try some spelling variations:
luoc can » luc canh, hoc can, luoc dai
luoc van » luoc va, luc van, luot van
cuu tre » cua tre, cau tren, cau treo
hanh di » hanh vi, hanh de, hang di
ve chat » va chat, van chat
hieu ve » hieu va, hieu van
ky dung » ly dung, ky dang, ky vung
sai ky » sac ky
ha hoi » hoa hoi, ha noi, xa hoi
di cuu » di cau, di cua, dinh cuu
tu sai » tu bai, tu san, tu cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sai ky dung ((ha hoi) or (hoa hoc)). hieu ve chat ((luoc van) OR (luoc can)) hanh di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sai ky dung ((ha hoi) OR (hoa hoc)). hieu ve chat ((luoc van) OR (luoc can)) hanh di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sai ky dung ((ha hoi) or (hoa hoc)). hieu ve chat ((luoc van) OR (luoc can)) hanh di cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sai ky dung ((ha hoi) or (hoa hoc)). hieu ve chat ((luoc van) OR (luoc can)) hanh di cuu tre*.