tough，adj.艰苦的;艰难的;棘手的;严厉的;强硬的;无情的;坚强的;健壮的;能吃苦耐劳的;
例句
It was a tough race and I had to pace myself.
这是场艰苦的比赛，我不得不控制好节奏。
tougher更严厉的，tough的比较级;
例句
The government insists that 'prison works' and plans to introduce a tougher sentencing policy for people convicted of violent crime.
