语法求助-2

还有今天的2道题，因为这些题都是新东方黄皮书上的，所以没有不能按提问格式发表帖子，不好意思。（红色为正确答案，蓝色是我的答案）

1. Today's nuclear fission fuels are the remnants of which used to be a much more active mixture of adioactive and fissionable materials two billion years ago and earlier.

2. Petrography concerns primarily with the detailed description and classification of rocks, whereas petrology deals primarily with rock formation.

试着答一下，请指正。

1.选A，which引导的定语从句不是修饰remnants.应改为：what.

2.选A,改为 is concerned, 如果用concerns,做及物动词，直接加宾语，后面不能有with.

恩，说得对，谢谢！