"She frequently falls ill" 是表示她经常生病的一种方式。
"Frequently" 是一个副词，意思是"经常地"。
"Falls ill" 是一个短语，意思是"生病"。
英文例句：
She frequently falls ill, so she has a lot of doctor's appointments.
中文翻译：她经常生病，所以她有很多看病的预约。
Despite her healthy pfestyle, she frequently falls ill with colds and flu.
中文翻译：尽管她的生活方式很健康，但她还是经常感冒和流感。