When I reached London I found waiting for me an urgent request that I should go to Mrs. Strickland's as soon after dinner as I could. I found her with Colonel MacAndrew and his wife. Mrs. Strickland's sister was older than she, not unlike her, but more faded; and she had the efficient air, as though she carried the British Empire in her pocket, which the wives of senior officers acquire from the consciousness of belonging to a superior caste. Her manner was brisk, and her good-breeding scarcely concealed her conviction that if you were not a soldier you might as well be a counter-jumper. She hated the Guards, whom she thought conceited, and she could not trust herself to speak of their ladies, who were so remiss in calling. Her gown was dowdy and expensive.
请教老师：上面节选，整体用了一般过去时，但为何在which the wives of senior officers acquire from the consciousness of belonging to a superior caste.中，谓语动词acquire用了一般目前时呢？这句是非限制性定语从句，其中acquire的宾语应该是and she had the efficient air 中的the efficient air吧？
这个非限制性定语从句是说话人作的补充说明。是记叙文中的议论部分。记叙部分用过去时，议论部分用一般目前时，由于议论的内容在说话人讲故事的时候还是成立的、或大伙认同的内容。
