下图装置（Ⅰ）是一种可充电电池，装置（Ⅱ）为电解池。

装置（Ⅰ）的离子交换膜只允许Na⁺通过，已知电池充放电的化学方程式为2Na₂S₂+NaBr₃Na₂S₄+3NaBr。当闭合开关K时，X电极附近溶液变红。下列说法正确的是（      ）

阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

    What was supposed to be ____ fun climb became a test of friendship for two young people from Canada last Saturday. Jeremy Savage and Ian Marshall, both aged 17, went ____ ____no problems.

    However, trouble began when they started the climb down the mountain. On one very ____ (danger) part of the path, Ian fell three meters off the side of the path. Jeremy was able to climb down to where Ian was. Ian was ____ (bad) injured and could not move. They had to wait and ____ (hope) that someone would come and help them. As the evening grew ____ (dark), Ian told Jeremy to leave him and go back to their parents, but he still did not leave. Jeremy thought ____ was not safe for Ian to be alone. The night was cold and windy, and Jeremy used his jacket and extra shirt to keep Ian warm.

    At sunrise, Jeremy decided that the only way ____ (help) his friend was to carry him. So they started the long climb back to their parents. Finally, after four hours, they arrived at the campsite ____ their parents were waiting, “I'll always remember what Jeremy did for me.” said Ian. “He saved my life.”

名著阅读。