当|a|≤1，|x|≤1时，关于x的不等式|x²﹣ax﹣a²|≤m恒成立，则实数m的取值范围是（　　）

用所给动词的适当形式填空。
(1)He____ (prefer) outdoor activities to films last year.
(2)No country ____ (make) such great progress as China in the past thirty years
(3) I called you this morning, but nobody answered it. Oh, I ____ (iron) shirts in the bedroom.
(4)We should prevent air pollution ____ (live) a happier life.
(5)We hope that more charity shows ____ (hold) to raise money for Project Hope.

一What does your sister usually do on Saturday mornings?一She often practices     English for half an hour．

从东汉末年以来，内迁的少数民族主要有匈奴、鲜卑、羯、氐、羌等，历史上合称“____”。