用括号里单词的适当形式填空。
It's(high) possible that humans have to move to Mars in the future.
此处用来修饰形容词 possible，应用副词 highly 表示“很；非常”。
_______ she is 3 years old,_______ she can dress herself.
Though; but
Because; so
Though; /
Because; /
尽管她三岁，但是她可以自己穿衣服。
根据题意，题干中含有一个让步状语从句，though不能和but同时连用，故选C。