Talks are under way to toughen trade restrictions.
加强贸易限制的会谈正在进行中。
《柯林斯英汉双解大词典》
2
They jab tree trunks to toughen their hands and practice squatting with other students sitting on their shoulders to build the leg strength.
他们猛击树干来锻炼双手，练习蹲坐，让其他同学坐在他们的肩膀上锻炼腿部力量。
3
Nevertheless, researchers have discovered that a process long known to discolor and toughen foods may also contribute to age related impairment of both cells and tissues.