You can't imagine what great trouble they have _____ the problem _____.You can’t imagine what great trouble they have _____ the problem _____.:a、to solve/being talked about b、 solving/ discussing c、 to solve/ to talk about d、 solving/being

You can't imagine what great trouble they have _____ the problem _____.You can’t imagine what great trouble they have _____ the problem _____.:a、to solve/being talked about b、 solving/ discussing c、 to solve/ to talk about d、 solving/being
You can't imagine what great trouble they have _____ the problem _____.
You can’t imagine what great trouble they have _____ the problem _____.
:a、to solve/being talked about b、 solving/ discussing
c、 to solve/ to talk about d、 solving/being discussed
句意我理解 但为什么用solving/being discussed

You can't imagine what great trouble they have _____ the problem _____.You can’t imagine what great trouble they have _____ the problem _____.:a、to solve/being talked about b、 solving/ discussing c、 to solve/ to talk about d、 solving/being
You can’t imagine 是主语,你不能想象,难以想象
what great trouble they have 是一个感叹结构,把它先变为正常句子结构,即：they have great trouble ..,他们.有着很大困难,后面跟(in) doing（in可以省略）
所以第一个空格填写solving
the problem 问题是“被讨论的”应该用被动语态,being discussed意思是“正在被讨论的”（被动语态的进行时）
所以综上所述,只有D是正确的

第一个空考查定语从句。 定语从句为they have _____ the problem _____.部分，其中考查词组：have troubel (in )doing sth. trouble作为先行词提前。第二个空考查词组：have sth. done 的结构，意为“使...被”

选择A [+(that)][+v-ing][

你好，这是一个复杂句，先找到句子的主句，you cant imagine .后面都是imagine的宾语。solving the problem 是imagine的主要宾语，imagine doing sth，所以用solving，being discussed 修饰the problem 表示正在被讨论的问题。整个句子就能解释通了，希望能帮到你。

D have troubel (in )doing sth. trouble
被讨论discussed