Perhaps you should try some spelling variations:
"cho vien code snippets" » "cho vien co snippets", "cho viec code snippets", "cho vienam code snippets", "chuc vien code snippets", "cho vien code slippers"
"python using a snippets" » "python using a slippers"
"locating bug code snippets" » "locating bug code slippers", "locating bung code snippets", "locating bugs code snippets"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("cho vien code snippets") or ("python using a snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("cho vien code snippets") OR ("python using a snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( cho vien code snippets ) or ( python using a snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("cho vien code snippets") or ("python using a snippets"))) or ("locating bug code snippets"))*.