the investigators discussed the results of their experiment for a long time__.

a) reach a decision---作出决定.agree to ---赞同.(----作不出彼此都能接受的决定)
b) 如果改成without coming to------就对了,因为being able to已经是多此一举了.
c) 和d)有了but in vain就足够了,后面就不能再写could they-----了,否则就是多此一举.
还有,a)中的agree to 应该写成agree on,因为:
1 agree with sb.
2 agree to对方开出的条件
3 agree on双方共同制定、决定的条款,协议,合同

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