Perhaps you should try some spelling variations:
le trung » do trung
trung xa » trung ha, trung va, trung ma
hanh vai » hanh vi, hanh va, hanh tai
su sach » so sach, vu sach
sach le » cach le, sach de, sach lo
hieu va » lieu va, hieu qua
cao suc » cao su
cao duc » dao duc, giao duc, tao duoc
va hanh » van hanh, va thanh, va danh
vai va » mai va, dai va, hai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach le trung xa hoi. hieu va ((cao suc) or (cao duc)) va hanh vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach le trung xa hoi. hieu va ((cao suc) OR (cao duc)) va hanh vai va thiet.
• Adding a wildcard symbol may retrieve word variants: su sach le trung xa hoi. hieu va ((cao suc) or (cao duc)) va hanh vai va thiet*.