Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cac loai » cac bai, cac giai, cac dai
lanh hai » manh hai, thanh hai, lang chai
tu cach » tu cac
hai cua » thai cua, dai cua, hoi cua
va lanh » va lang, va danh, va hanh
cac lao » ca lao, cac giao, cac lang
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky nang xa hoi. hieu vien ((cac lao) OR (cac loai)) va lanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang xa hoi. hieu vien ((cac lao) OR (cac loai)) va lanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky nang xa hoi. hieu vien ((cac lao) OR (cac loai)) va lanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang xa hoi. hieu vien ((cac lao) OR (cac loai)) va lanh hai cua tre*.