to be so used to somebody/something that you do not recognize their true value any more and do not show that you are grateful（因习以为常）对…不予重视；（因视为当然而）不把…当回事
Her husband was always there and she just took him for granted.她丈夫随时都在身边，她只是认为他理应如此。
We take having an endless supply of clean water for granted.我们想当然地认为洁净水的供应是无穷无尽的。