第 1 题 · 四级
The mechanic fixed the broken car, which the owner had waited for a week.
核心词：mechanic məˈkænɪk n. 机械师
机械师修好了抛锚的汽车，车主等了一周。
过去完成时过去式 + which 从句（过去完成）短语 a car mechanic短语 fix the car
The ___ fixed the broken car, which the owner had waited for a week.
第 2 题 · 四级
The meeting followed a strict protocol, which every guest had to obey.
核心词：protocol ˈprəutəkɒl n. 礼仪；议定书
会议遵循严格礼仪，每位来宾都必须遵守。
一般过去时follow + which 从句 + have to obey短语 a strict protocol短语 diplomatic protocol
The meeting followed a strict ___, which every guest had to obey.
第 3 题 · 四级
Building the bridge was costly, which the city had to pay for slowly.
核心词：costly ˈkɒstli adj. 昂贵的
建这座桥代价高昂，城市不得不慢慢偿还。
一般过去时动名词主语 + costly + which 从句 + pay for短语 be costly短语 a costly mistake
Building the bridge was ___, which the city had to pay for slowly.
