填入下列文段空白处的词语，最恰当的一组是（ ）21世纪不仅面临着巨大危险， ① 还拥有巨大潜力。 ② 历史学家们没有魔法师的水晶球，不能确定无疑地预知将来， ③ ，他们能比较确定地预测到，21世纪既不是乌托邦， ④ 不是地狱， ⑤ 一个拥有各种可能性的世纪。 ⑥ 这些可能性中的哪些能够实现取决于当代的年轻人，你们在未来几十年中的所作所为将是有决定意义的。 ①②③④⑤⑥

We are now living in _______ world wherecomputers rule our work and daily life．So online searches have already become _______must．

r your timely warning,we into greattrouble.—You know we’re friends.

I find our teacher is rather strict ___________ us.—-Actually, my boy, your future boss will be cruel _________ you

Mr. Wang would have continued to lead _____ poor life instead of changing his lifestyle if he hadn’t met Mr. Smith by _____ chance who was a businessman.