单选题 The house was very quiet, ______ as it was on the side of a mountain.
A. isolated B. isolating
C. being isolated D. having been isolated

【正确答案】 A

【答案解析】[解析] 结构识别
逗号后面的部分是原因状语从句as it was isolated on the side of a mountain，本句为了强调“被隔绝”之意，将isolated提前；因此A为答案。