简单的英语语法:389 is the number of days in a year (365) added to the number of months twice (24).请问这里的twice在句中充当什么成份?修饰什么的?

问题描述:

简单的英语语法:389 is the number of days in a year (365) added to the number of months twice (24).
请问这里的twice在句中充当什么成份?修饰什么的?