Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
hanh dai » hanh tai, hanh dao, vanh dai
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
su cac » tu cac, su cao, su can
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: su cac ky ((nang ma) or (nang x)) hoi. hieu ve cac thuc day hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su cac ky ((nang ma) OR (nang x)) hoi. hieu ve cac thuc day hanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: su cac ky ((nang ma) or (nang x)) hoi. hieu ve cac thuc day hanh dai cua tre*.