404. That’s an error.

The requested URL /translate_c?hl=en&ie=UTF-8&sl=en&tl=ru&u=http://en.wikipedia.org/w/index.php%3Ftitle%3DSubstitution_model%26action%3Dedit%26section%3D4&prev=_t&rurl=translate.google.com&twu=1&usg=ALkJrhjsmV1Yrv0nyFq-CYLaEPrRCAOPTw was not found on this server. That’s all we know.