Perhaps you should try some spelling variations:
vien cay » vien cac, vien xay, vien can
vien cao » vien cac, vien dai, vien da
thuc dan » thuc hanh, hoc dan, thuc vat
dan hanh » dang hanh, dan khanh, dan thanh
vu sach » vu bach, su sach, vu khach
ty nang » ty xang, ty hang, ly nang
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ((ty nang) OR (ky nang)) x hoi. hieu ((vien cay) or (vien cao)) thuc dan hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ((ty nang) OR (ky nang)) x hoi. hieu ((vien cay) OR (vien cao)) thuc dan hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ((ty nang) OR (ky nang)) x hoi. hieu ((vien cay) or (vien cao)) thuc dan hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ((ty nang) OR (ky nang)) x hoi. hieu ((vien cay) or (vien cao)) thuc dan hanh vi cua tre*.