We all suggested the plan ________, but the boss insisted that his plan ________ perfect．
A.put off; wasB.should put off; isC.be put off; wasD.should be put off; is在线课程C
解析：
suggest(建议)后面接虚拟从句(should be done)；
insist在这里是：坚持认为。后面的从句是真实的叙述，其时态与主句时态范围一致。