You mustn't believe the news,it can't be true.该句中mustn't似乎也妥,表示可能性,即“不可能”.为何只能用can't呢?

You mustn't believe the news,it can't be true.该句中mustn't似乎也妥,表示可能性,即“不可能”.为何只能用can't呢?
You mustn't believe the news,it can't be true.
该句中mustn't似乎也妥,表示可能性,即“不可能”.为何只能用can't呢?

You mustn't believe the news,it can't be true.该句中mustn't似乎也妥,表示可能性,即“不可能”.为何只能用can't呢?
mustn't在表示否定词义的时候是“禁止,不许可”的意思.
而can't才是“不可能”的意思.

因为主语是IT