老师注意到孩子上课时注意力不集中，可能是由于多动症。

The teacher noticed the child's difficulty focusing in class, possibly due to ___hyperactivity.

医生诊断这个孩子患有多动症，因为他的过度活跃让他在课堂上难以集中注意力。

The doctor diagnosed the child with ADHD because his ___hyperactivity made it hard for him to focus in class.

咖啡因会导致某些人的神经系统过度活跃。

Caffeine can cause ___hyperactivity in some people's nervous systems.