The threat of losing their jobs is a constant source of worry to them.

丢掉工作的威胁时常使他们忧心忡忡。

《牛津词典》

Throughout the house, the views are a constant source of surprise and delight.

整个房子，目之所及不停带来惊奇和欣喜。

《柯林斯英汉双解大词典》

Learning to be mature and sensible can prevent us from becoming a constant source of worry to them.

学着变得成熟和理智可以防止他们不断为我们担心。

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"He's been a constant source of inspiration for the project, " the Biophilia project co-ordinator James Merry said.

BBC: Bjork opens Manchester International Festival

The death of so many young women is a constant source of fear.

BBC

If close relationships trigger attachments that ground people, then a phone is a constant source of reinforcement as it consistently dispenses rewards.

FORBES: Love, Sex and Your Smartphone