Perhaps you should try some spelling variations:
tuan tai » toan tai, quan tai, tan tai
van tuan » van quan, van ban, anh tuan
nang dau » hang dau, xang dau, nang du
tai cua » thai cua, tai cuc, tri cua
luc van » luoc van, luu van, duc van
cau luc » cau truc, cau phuc
hieu ve » hieu va, hieu van
dau hoi » cau hoi, dai hoi, dan hoi
sach ky » sach y, sach kem, sach hay
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ve cau » ke cau, va cau, ve cac
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((((sach ky) or (sac ky))) or (sach ty)) nang dau hoi. hieu ve cau luc van tuan tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((((sach ky) OR (sac ky))) OR (sach ty)) nang dau hoi. hieu ve cau luc van tuan tai cua tre*.