Many of the colleges announced that they were pausing in-person classes after students or staff members tested positive for the virus.
after students or staff members tested positive for the virus 这个时间状语从句,应该是宾语从句的一部分,它是宾语从句的时间状语,应该修饰 were pausing,这是结构决定的。如果修饰 anounced 的话,其位置应该在句首,以免产生歧义。
我仔细看了一下这句子,after 从句应该是修饰主句 announced,因为after从句使用名词students or staff members作主语,而宾语从句使用代词 they 作主语。所以从这个角度看,应该是修饰主句谓语动词。