【题目】The instrument _____ to test the new drug was a great success, which excited the local people.
A.designing
B.to design
C.designed
D.was designed

【答案】C
【解析】句意：被设计用于检测这种新药的仪器是一个巨大的成功，这使得当地人非常的兴奋。The instrument与design之间是被动关系，所以用过去分词作定语，选C。