that...to loud noises for a long time will slow the deverlopment of speech in ba babies是宾语从句,being exposed to loud noises for a long time（长期处于嘈杂的环境中）是从句的主语.
分词不能做主语,只有名词、代词、名词性短语、从句才可以做主语.排除B.
being exposed 与动作的执行者是被动关系,被动语态的结构是“be+过去分词”,在非谓语动词中去掉be.排除A.
having exposed是主动语态的现在完成时在非谓语动词中的表现形式.排除D.
第二题选C.measure在这里作不及物动词,有...长(或阔、高等) .
measuing about 6400 kilometers,是现在分词短语作状语,表示伴随情况.