But inside, special windows cut power bills by blocking solar heat in summer and retaining indoor warmth in winter.
出自-2013年6月阅读原文
英语六级真题
first, keeping up with the pace of technological change; recruiting high-quality staff in a time of skills shortages in it as a whole and in a highly competitive market; and the issue of retaining staff once they've been recruited and trained.
2016年12月六级真题（第二套）听力 Section C
Now, though a novel type of steel has been developed that resists fractures at much lower temperatures, while retaining its strength and toughness-without the need for expensive additives.
2019年6月六级真题（第三套）阅读 Section A
柯林斯高阶英汉双解学习词典释义
VERB
保留;保持;保存
To retain something means to continue to have that thing.