This is the most common cause of abnormal heartbeat in older adults.

VOA: special.2009.08.12

Malaria causes a million deaths per year, and schistosomiasis, which is a parasitic disease, is unfortunately a common cause of death in the world.

疟疾每年造成一百万死亡,而血吸虫病,这是一种寄生虫病,不幸的是,它是世界上很常见的死因

耶鲁公开课 - 生物医学工程探索课程节选

The most common cause of COPD is long-term smoking or years of exposure to second-hand smoke.

VOA: standard.2010.06.21

But the most common cause is long-term smoking or years of breathing other people's smoke.

VOA: special.2010.06.23

Down syndrome is the most common genetic cause of mental retardation.

VOA: special.2009.09.09