公司名稱與大型機構相同？？？？？？？

You are having an unlimited company i.e. sole proprietor or partnership. There is no restriction of the registration of names under the Business Registration Ordinance. You could notice that there are a lot of firms with the same name.
However, if you are using a name quite similar to the name of a big and well-established business and if there is also a trade mark or brand name used by that corporation, they may stop you from using the name, an infringment.
In general, since you are doing a different business with the name of your company showing the trade thereof, it is OK then.

跟據公司註冊條例無限公司同有限公司可以同名，因為係最尾你會用公司兩隻字人地用有限公司四隻字．　除非你同佢都係同類公司即係有限公司，咁一定唔會同名．　你可以改名叫長江ｘｘ公司，但係人地個間叫長江ｘｘ有限公司．