by implementing which the level of daily operation and manag

你好, 这句话的关键在于, 关系代词" which" 所引导的非限定性定语从句用来说明前面整个句子的情况或者主语的某一部分.
在远句中,"which" 代指之前提到的几项措施：A; B; C; D; E; and F
代入, 意思上是by implementing A;B;C;D;E;F, the level of daily operation and management of the Department of Engineering in the Datang Four Seasons Garden has been improved.
但是英语语言表达上是by implementing which...
意思为:
[通过实施A; B; C; D; E; F几大建议, 大唐四季花园工程部的日常运作管理水平得到了提升.]
希望这样解释能够对你有所帮助.