无怪[wú guài]
词典no wonder：无怪；难怪，怪不得。
词典not to be wondered at：无足为奇；无怪。
no wonder; not to be wondered at:
例：他进行了彻底的调查。无怪他对此事了解很多。
He had made a thorough investigation. No wonder he knew so much about it.