许多同学都有自己的电子邮箱，如168@sina.com, pgbook@ 163.com, hifriend998 @ 126.com 等。请问其中的@表示什么意思，该怎么读

.—Did yourfather come back early last night—Yes. It was not yet eight o’clock ______he arrived home.

What do you think of Wilson’s speaking–No one does _______ in our school.

Garth Brooks’ records sell well. He has sold more than 120 ____ records. –But I still hope to see him live one day.

The disaster-stricken village was inaccessible _______ by helicopter, and the storm added to the rescuers’ difficulty