底线是，人们吸烟会使健康面临风险。

___The ___bottom ___line is that people's health is at risk if they smoke.

底线是，今天的成年人必须停下来想一想他们在做什么。

___The ___bottom ___line is that the adults of today have to stop for a second and think about what they are doing.

底线是，我们需要减少碳排放以应对气候变化。

___The ___bottom ___line is that we need to reduce carbon emissions to combat climate change.