Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
cao luc » bao luc, cao duc, cao suc
vai cua » hai cua, lai cua, bai cua
luc van » luoc van, luu van, duc van
hieu va » lieu va, hieu qua
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
va cao » va cac, va co, va dao
ha hoi » hoa hoi, ha noi, xa hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sinh) or (hoc sach)) ky lang ha hoi. hieu va cao luc van hanh ((vai cua) OR (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sinh) OR (hoc sach)) ky lang ha hoi. hieu va cao luc van hanh ((vai cua) OR (dai cua)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sinh) or (hoc sach)) ky lang ha hoi. hieu va cao luc van hanh ((vai cua) OR (dai cua)) tre*".