同位语从句中什么时候用that 什么时候用whether? 急！！！

Question

看两个同位语从句：
1. The mother was filled with anxiety _____ her daughter might be disabled by the accident.
A. whether B. that C. what D. which 这题选A
2. A growing anxiety is disturbing the public _____ the economy will continuously decline.
A. which B. that C. why D. whether 这题选B
问：同样都是anxiety的同位语，为什么 第一个选whether，而第二个选that

Answer 1

根据语义，第一题是the mother担心她女儿是否会变残疾，而第二题后面的经济持续下降是前面的后果，是确定的

Answer 2

第一个wether有是否的意思，第二个没有是否的意思