Perhaps you should try some spelling variations:
hanh trang » thanh trung, minh trang, tinh trang
hanh trinh » hanh chinh
hien xanh » hien hanh, hien nhanh, chieu xanh
trong bai » trong ban, thong bai, trong hai
cua dung » cua dang, cua dong, qua dung
bai toan » bai tap
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hien xanh - ((((hanh trang) OR (hanh trinh))) or (canh tranh)) cua dung trong bai toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien xanh - ((((hanh trang) OR (hanh trinh))) OR (canh tranh)) cua dung trong bai toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - ((((hanh trang) OR (hanh trinh))) or (canh tranh)) cua dung trong bai toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - ((((hanh trang) OR (hanh trinh))) or (canh tranh)) cua dung trong bai toan cau*.