1. Some scientists speculate the reduction in mental function often attributed to getting old may really be a penalty of neglecting to stay physically active, in addition to related factors such as medicines and poor diet.
    一些科学家推测，除了药物作用和饮食不当等相关因素外，常常归咎于衰老的大脑功能下降实际可能是对不注意保持体育运动的一种惩罚。

2. I can only speculate that he left willingly.
    我看他一定是自愿走的.