Perhaps you should try some spelling variations:
qua tham » qua cham, qua than, qua thanh
thanh di » thanh doi, thanh de, thanh do
hoc ban » hoc bang, hoc dan, hoc bai
soc ban » coc ban, so ban, soc ba
ky tang » ky nang, ky dang, kho tang
hoa hoi » khoa hoi, hoa hoc, hoa doi
cua tre » cua te, cuu tre, cua triet
ha hoi » ha noi, xa hoi, va hoi
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cac ky tang ((ha hoi) or (hoa hoi)). hieu qua tham ((soc ban) OR (hoc ban)) thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky tang ((ha hoi) OR (hoa hoi)). hieu qua tham ((soc ban) OR (hoc ban)) thanh di cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky tang ((ha hoi) or (hoa hoi)). hieu qua tham ((soc ban) OR (hoc ban)) thanh di cua tre*".