半途而废 give up halfway; do a thing by halves; leave sth. unfinished 这项试验一定要搞到底, 不能半途而废。 we must carry the experiment through to the end, not give up halfway. 他不是那种做事半途而废的人。 he is not such a man as would leave his work half done
半途换马 change horses halfway; swap horses while crossing a stream -- to change leadership in difficult times