GRE

简答题It’s such a___________concept that it seems to have been around for all time,but packaged sliced bread has only beenavailable since the late 1920s.

参考答案:暂无进入在线模考
C
The clue here is“it seems to have been around for all time.”That would not describe something radical(choice A)or flesh(choice B),but it could describe something primitive(choice C).