请教新东方语法教程练习11的两道题

31. A partrilineal extended family consists of core group of males, their wives, and their unmarried daughters.

答案是B。core group的名词词组搭配不对吗？应该怎么改呢？

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

答案是A。也要改成deals吗？

31. B 改为of the core

40. 是的