These scientists are working hard to make our country -----.

选A
make 的用法：
1、make sb./sth.+ 名词或形容词（作make的宾语补足语）
例：We made him president of the country.（president名词作宾补）
He worked hard to make his parents proud.（proud形容词作宾补）
2、make sb.do sth.后接省略to的不定式
例：The touching story made us all cry.
题目考的是第一种用法.