请教语法 01-01-37

cicimiracle

Wampum,beads used as (a form) of exchange (by) some Native Americans,was made of (bits of) seashells cut,(drill),and strung into belts.
我选的是D，我觉得应改为drilled.可答案为什么是C呢？不明白啊

marshial

是D错了，楼主最好下载太傻语法笔记，以便核对！！