A．The impact of smoking lasts less than 30 years.
B．Smoking has a long-term impact on Our molecular machinery.
C．Damages caused by smoking can never be cured.
D．Ailments are mainly caused by damage to the DNA.

A．They checked the lungs of 16,000 people.
B．They examined the heartbeats of 16,000 smokers.
C．They measured the blood pressure of 16,000 smokers.
D．They looked at blood samples from 16,000 people.

A．The effects of smoking on their DNA still exists.
B．The damage to their DNA will be cured one year later.
C．The function of their DNA has been changed.
D．The chance of having cancer is still high.