Perhaps you should try some spelling variations:
"duong cong cao snippets" » "dung cong cao snippets", "luong cong cao snippets", "duong trong cao snippets", "duong cong cau snippets", "duong cong cac snippets", "duong cong co snippets"
"dung java java snippets" » "dung va java snippets"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core 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: (((("duong cong cao snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("duong cong cao snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( duong cong cao snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("duong cong cao snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.