It was not until…that…是强调句式。 It was not until yesterday that I noticed it. 直到昨天我才注意到这件事。 until用于肯定句表示“直到……”，主句谓 语动词用延续性动词。 She’s worked as a nurse until past her sixtieth birthday. 她当护士一直到过了她的60岁生日。