C 本题考察的是形式主语的用法
首先可以排除A、B,A的this不正确,形式主语一般的只能用it ,B在时态上产生了错误
之所以在C和D中选C,是因为句末用的是“in the field”,这是个地点状语,而原句显然是讲：在那个平原上已没有任何机会能让他的考察团有所突破了.
PS：我下面说的there作形式主语只是为了便于你的理解,其实there不能说它就是形式主语
there doesn't seem to be .和 it doesn't seem to be.,there和it都可以作“形式主语”,（注意,我只是说可以,因为原题正是采用了形式主语的用法.真正用了没还得看句子本身,我下面有句例句可以供你参考）真正的主语是后面there或it所指代的内容,it通常指代具体的事物,而there则指代地点状语
这句话真正的主语是“in the field”,原句去掉there这个“形式主语”,实际上====In the field doesn't seem to be much chance for his research group to make breakthrough.
再给你看it doesn't seem to be 的例句：It doesn't seem to be a good day for him to go jogging today.真正的主语是today===Today doesn't seem to be a good day for him to go jogging.
当然了,如果把例句中today去掉,it 就可以变成真正的主语,可以自己体会一下