A product or service which is a regular source of income for a company is called a cash cow.

华尔街上的大铜牛应该跟这个成语有一定的联系吧，寄望于股票像摇钱树一样财源滚滚。

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Yes, getting news from Internet is a regular source now because it's very convenient for me to get news from Internet such as mobile phone.

是的，从互联网获取新闻是一个普通的来源，因为现在从网上比如手机上看新闻非常方便。

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Because hunger may be overlooked as a headache source, one must make a habit of regular meals.

由于饥饿可能是一个被忽视的头痛起因，所以一个人必须养成规律饮食的习惯。

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Bank of America is still dealing with its legacy mortgage issues which have been a regular source of concern for the company over the last 3 years.

FORBES: Taking Stock of Bank of America's Mortgage Business

Like UPS, these companies have the trucks (their product lines) and the drivers (their sales force) and what they need now is a regular source of new packages (products) to deliver to customers.

FORBES: Software PACMAN

The poll, in which party members elect representatives to serve on the executive, has in past years been a regular source of embarrassment to the leadership with Labour's rank and file spurning slates of Blairite candidates in favour of left-wingers.

BBC: Labour row looms on internal polls