they could have come to your help,but they_____in a traffic jam A had been caught b should catch

对不起,是我理解错题意了
选C
解析：这是一个虚拟语气,表示对现在事实的虚拟表示与过去事实相反的情况 结构为：主语+过去时+其他+主语+should/would/could/might+do+其他 例：
1.If I were you,I would take an umbrella.如果我是你,我会带把伞.（事实：我不可能是你）
2.If I knew his telephone number,I would tell you.如果我知道他的电话号码,我就会告诉你.（事实：不知道）
3.If there were no air or water,there would be no living things on the earth.如果没有水和空气,地球上就不会有生物.(事实：地球上既有空气也有水)
4.If I had any money with me,I could lend you some.如果我带钱了,我就会借给你些.（事实：没带钱）
5.If he studied harder,he might pass the exam.如果他再努力些,就能通过考试了.（事实：没有努力
虚拟语气是很重要的一个语法,
翻译：他们本来应该来帮助你的,但是他们被卷入了让一场交通事故问一个额外的问题 he insisted that a medical team _____to the flooded immediately. aissent bbesent答案是A　　　但是大家都说是B由insist that + （should） do 构成的虚拟语态从句 ，should 可以省略，即：insist+动词原形这个题我选A