اِسْتَظْهَرَ: حَفِظَ عَنْ ظَهْرِ قَلْب to memorize, learn by heart, commit to memory, con; to know by heart

اِسْتَظْهَرَ بـِ: اِسْتَعَانَ to seek (ask for, call for, appeal for) the help (assistance, aid, support) of; to turn to for help; to get help from

اِسْتَظْهَرَ على: غَلَبَ to overcome, overpower, get the better of, defeat