Perhaps you should try some spelling variations:
trinh truoc » trinh truong, trinh thuc, trinh trung
hanh trinh » canh tranh, hanh chinh
truoc cac » truoc cach, truoc cang, truoc cuoc
trinh thi » trinh tai, dinh thi, trinh tu
canh khoa » anh khoa, xanh khoa, doanh khoa
khoan he » khoan ke, khoan le, khoan hoi
thi canh » thi hanh, thi anh, thi oanh
tu hanh » du hanh, lu hanh, thuc hanh
te hanh » te thanh, ve hanh, te danh
khoa he » hoa he, khoa hoc, khong he

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu hanh trinh truoc cac khoan he thong ) or ( te hanh trinh thi canh khoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu hanh trinh truoc cac khoan he thong ) OR ( te hanh trinh thi canh khoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu hanh trinh truoc cac khoan he thong ) or ( te hanh trinh thi canh khoa he thong ))*.