请教英文知识I'm afraid that I can't get up我恐怕站不起来了I'm afraid I can

请教英文知识
I'm afraid that I can't get up我恐怕站不起来了
I'm afraid I can't hear you我恐怕听不到你在说什么
这两个句子中为什么前句用了that而后句可以不用呢?