Marx and Engels have forged in the struggle sincere and selfless friendship, so that they sincerely cooperate closely and co-authored a number of classics of scientific socialism.

• 马克思与恩格斯在斗争中结下真诚而无私的友谊，使他们精诚合作，亲密无间，共同撰写了许多科学社会主义经典著作。