扫描二维码，直接登录
题库 / OG2017V-SC-225
As a result of record low temperatures, the water pipes on the third floor froze, which caused the heads of the sprinkler system to burst, which released torrents of water into offices on the second floor.
which caused the heads of the sprinkler system to burst, which released torrents of water
which caused the heads of the sprinkler system to burst and which released torrents of water
which caused the heads of the sprinkler system to burst, torrents of water were then released
causing the heads of the sprinkler system to burst, then releasing torrents of water
causing the heads of the sprinkler system to burst and release torrents of water
还没有题目讲解（毕出老师会陆续发布对官方考题的解读，请保持关注）。
1）Sequences of actions are normally in parallel. If two description happened at the same time, they shouldn't be parallel. Instead, use "comma + ing" to modify.
2）", then ing…" is NOT right, because the action of "comma + ing" is in the same time-frame as the main verb.
登录 或 注册 后可以参加讨论