know on which side one's bread is buttered

knows on which side one's bread is buttered 三单 knowing on which side one's bread is buttered 现在分词 knew on which side one's bread was buttered 过去式 knew on which side one's bread is buttered 过去式 known on which side one's bread was buttered 过去式 known on which side one's bread was buttered 过去分词 known on which side one's bread is buttered 过去式 known on which side one's bread is buttered 过去分词