There must be a reason why Xenicibis had such strange wings.

始祖鸟拥有如此奇怪的翅膀一定事出有因。

youdao

You see there must be a reason why the person has achieved success.

为什么?你觉得那人成功肯定是有原因的。

youdao

Jack remains at the abandoned field because he knows there must be a reason why the power is going to be turned off.

杰克想留在荒芜的旷野中，因为他觉得，将这个地段的电力切断肯定是有原因的。

youdao

There must be a compelling reason why they should hire you to manage and implement it, as opposed to using a current employee.

FORBES: Magazine Article

There must, however, be a reason why hiccuping persists 370 million years after animals started hauling themselves onto the land.

BBC: Why we hiccup

It became a carrot to coax the DPJ into supporting the LDP's legislation before Mr Aso trumped up a new reason why an election must be held off for the public good.

ECONOMIST: Japan's beleaguered prime minister calls an election