件维护活动包括以下几类:改正性维护、适应性维护、【 】维护和预防性维护。 发布时间:2021-12-20 09:33 │ 来源:www.tikuol.com 题型:填空题 问题: 件维护活动包括以下几类:改正性维护、适应性维护、【 】维护和预防性维护。
题型:填空题 Though the problems were all very hard, Kate kept on working on them she finally solved all of them. [ ]A. beforeB. until C. whenD. after 查看答案