Perhaps you should try some spelling variations:
toan tap » toan ban
bai toan » bai tap
pham dap » pham dac, nham dap, pham dat
tu sach » thu sach, su sach, te sach
tap cua » tap quan, tiep cua
dap bai » tap bai, cap bai, dao bai
va pham » van pham, va phat, va phap
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa

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) or (hoc sinh)) ky ((nang xa) OR (nang ma)) hoi. lieu va pham dap bai toan tap cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (hoc sinh)) ky ((nang xa) OR (nang ma)) hoi. lieu va pham dap bai toan tap cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (hoc sinh)) ky ((nang xa) OR (nang ma)) hoi. lieu va pham dap bai toan tap cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (hoc sinh)) ky ((nang xa) OR (nang ma)) hoi. lieu va pham dap bai toan tap cua tre*.