选出正确的词，并写在横线上。

1. —Have you ever been to Europe?    —No, but I ______ (have been/went) to Africa last year.

2. —Have you ever been to my house?   —No. But I'm coming to your party ______ (tonight/this night).

3. Has Victor ______ (been ever/ever been) to China?

4. In future, people will ______ (spend/waste) a long vacation every year.

5. He is an ______ (exchanged/exchange) student in this school.

系统中有多个中断同时发生时，系统将根据中断优先级来响应优先级最高的中断请求。若要调整中断事件的响应次序，可以采取的措施是( )。

A．中断向量

B．中断嵌套

C．中断响应

D．中断屏蔽