Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va, hieu van
lang xa » lang ha, lang van
sai ky » sac ky
ve cam » ve cham, ve cac, va cam
de cua » te cua, dieu cua
le cua » ly cua
te sai » te tai, te bai, te lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sai ky ((lang xa) or (dang xay)) hoi. hieu ve cam duc van hanh ((de cua) or (le cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sai ky ((lang xa) OR (dang xay)) hoi. hieu ve cam duc van hanh ((de cua) OR (le cua)) tre.
• Adding a wildcard symbol may retrieve word variants: te sai ky ((lang xa) or (dang xay)) hoi. hieu ve cam duc van hanh ((de cua) or (le cua)) tre*.