Perhaps you should try some spelling variations:
"dung trinh toan snippets" » "dung tinh toan snippets", "dong trinh toan snippets", "cong trinh toan snippets", "dung thanh toan snippets", "dung trinh han snippets"
"using cfd code snippets" » "using 3d code snippets", "using c code snippets"
"locating bug core snippets" » "locating bug 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: (((("using cfd code snippets") or ("dung trinh toan snippets"))) or ("locating bug core snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("using cfd code snippets") OR ("dung trinh toan snippets"))) OR ("locating bug core snippets")).
• Removing quotes may allow a broader search: (((( using cfd code snippets ) or ( dung trinh toan snippets ))) or ( locating bug core snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("using cfd code snippets") or ("dung trinh toan snippets"))) or ("locating bug core snippets"))*.