BOC(HK), the local arm of Bank of China, ”the local arm” 點解?

For a human body, the arm refers to the upper limb.
For a tree, the arm refers to the branch(樹枝)
For a company, the arm refers to the branch(分公司) or subsidiary(子公司或附屬公司)
Local refers to here Hong Kong(本地).
So「the local arm」refers to Bank of China's( head quarters in PRC) subsidiary company located here in Hong Kong. It is called BOC (HK).

"一個本地的分部"

BOC(HK)是Bank of China在香港的一個本地分部

A subsidiary or brunch of BOC


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