안녕하세요~
13. only after he had acquired considerable facility in speaking, he began to learn to read and write.
왜 네번째 밑줄 부분이 틀린건지 잘모르겠어요~
15. it was her who represented her country in the united nations and later became an ambassador to the united states.
왜 두번째 밑줄이 틀린거죠?