Perhaps you should try some spelling variations:
pham day » phap day, pham duy, pham xay
bai toan » bai tap
toan tap » toan ban
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
va pham » van pham, va phat, va phap
day bai » dao bai, dap bai, day ban
tap cua » tap quan, tiep cua
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) or (hoc sinh)) ky nang xa hoi. lieu va pham day 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 hoi. lieu va pham day bai toan tap cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (hoc sinh)) ky nang xa hoi. lieu va pham day bai toan tap cua tre*.