Perhaps you should try some spelling variations:
cac thoi » cac toi, cac hop, cac tro
dang xay » dang van, van xay
tinh vai » tinh va, tinh hai, tinh bai
cap nuoc » dat nuoc
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
va tinh » may tinh
hieu va » lieu va, hieu qua
lang ha » long ha
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 sach y ((dang xay) or (lang ha)) hoi. hieu va ((cac thoi) or (cap nuoc)) va tinh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((dang xay) OR (lang ha)) hoi. hieu va ((cac thoi) OR (cap nuoc)) va tinh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((dang xay) or (lang ha)) hoi. hieu va ((cac thoi) or (cap nuoc)) va tinh vai cua tre*.