Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
dieu tra » dieu tri, dieu cua
thuc day » thuc dan, thuc vat
tu sach » thu sach, te sach, tu cach
hiem he » hiem xe, hieu he, thien he
dong ho » dong hoc, dong hoa, dong cho
ky dong » ly dong, ky dang, ky cong
su sach » so sach, vu sach
ho hoi » hoc hoi, hoa hoi, hoi hoi
he am » he nam, ve am

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 (su sach)) ky dong ho hoi. hiem he am thuc day thanh ((dieu tra) or (kiem tra)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky dong ho hoi. hiem he am thuc day thanh ((dieu tra) OR (kiem tra)) tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky dong ho hoi. hiem he am thuc day thanh ((dieu tra) or (kiem tra)) tre*.