单选题 Houses in this city are twice ______ expensive ______ they are in other cities.

【正确答案】 A
【答案解析】[名师精解] as…as…同级比较结构前可加副词twice，three time：等来表示“多出几倍”的意思。
[解题秘籍] 也可用twice more than来表达。