They won't have gone to the gym without us.
问题描述：
They won't have gone to the gym without us.
我也是这么理解的，可是答案里与其与其意思相同的居然是这句I doubt they'd leave for the gym without us.
答
没有我们他们不会去健身房
答案对的：我对他们去健身房（在没有我们的陪伴下）的这件事表示怀疑.
意思就是说,没有我们,他们没可能去健身房.