丢之脑后丢在脑后diū zhī nǎo hòu

banish from one’s memory (/mind); cast behind one’s back;commit to oblivion; ignore and forget/……他在大革命时，并未诚意地实行过三大政策。在内战时，更将三民主义～。(《周恩来选集》上—152) …he never sincerely carried out the Three Great Policies in the period of the Great Revolution,and he ignored the Three People’s Principles completely in the period of civil war.