Perhaps you should try some spelling variations:
hinh thai » sinh thai, tinh thai, dinh thi
hanh thai » nhanh thai, hanh tai, anh thai
cua tre » cua te, cuu tre, cua triet
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
nang o » nang co, nang ho, nang ro
tu san » thu san, tu ban, tu can
o lai » o lao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cac) or (tu san)) ky nang o lai. hieu ve cac duc van ((hanh thai) or (hinh thai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cac) OR (tu san)) ky nang o lai. hieu ve cac duc van ((hanh thai) OR (hinh thai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu cac) or (tu san)) ky nang o lai. hieu ve cac duc van ((hanh thai) or (hinh thai)) cua tre*.