Last term,Peter was ____ at home.His parents were doing busines in another city. He felt lonely,so he often turned on the computer and played computer ____. However, sitting in front of the computer for a long time is ____ for him. And he spent little time on his study.He failed his exams.Luckily,his parents ____ his problem in time.They decided to come back home.Peter studies hard now.So far,he has made progress in his study.He ____ he can catch up with his classmates soon.

①清朝名臣谢济世，一生四次被诬告，三次入狱，两次被罢免官职，一次充军，其经历之坎坷，令人不忍卒读。

②韩国同意美国在其领土布置“萨德”反导系统，无疑火中取栗，这样做定会使自己成为大国博弈的牺牲品。

③冰岛已成为本届欧洲杯当仁不让的黑马，要知道，他们在最后两场比赛中战胜的奥地利队和英格兰队都是世界强队。

④他是我国历史上著名的学者，但相关史书并没有留下有关他的详细记载，人们只能从前人的闲言碎语中了解他。

⑤那里地处热带，白天太阳灼人，街上不见人影；夜市则灯火通明，人声鼎沸，货架和地摊上，物品琳琅满目。

⑥他们用年轻的生命换取新中国温暖的阳光，自己却在黑暗中心甘情愿地忍受着百般折磨直至献出生命，他们死得其所。

足量铜与一定量浓硝酸反应，得到硝酸铜溶液和NO₂、N₂O₄、NO的混合气体，这些气体与1.68L O₂（标准状况）混合后通入水中，所有气体完全被水吸收生成硝酸．若向所得硝酸铜溶液中加入5mol•L^﹣1 NaOH溶液至Cu²⁺恰好完全沉淀，则消耗NaOH溶液的体积是（   ）