英语题求助,请写清理由,在线等,急,谢谢!

66题的答案是：They found the first ―word‖ that they could understand in that language.

而我写的是：That those small parts are really messages.

68题的答案是：What the DNA is and how we understand it.

而我写的是：What DNA is and how find out it.

请各位老师帮忙看一下我写的对吗?如果不对的话,请各位老师讲一下我错在哪里了,谢谢!