1. When am I allowed to leave the hospital?

我什么时候能出院？

还能这样说：

When can I be discharged?

How soon can I be released from the hospital?

应用解析：

allow for sb./sth. 在计算、估计、考虑时包括某人或某事物；

allow of sth. 容许某事物；对某事物留有余地；

allow of no excuse 不容辩解

2. It's hard to say. It depends on your recovery.

很难说，这得看你的恢复情况了。

还能这样说：

It's difficult to say. If you have a good recovery, you can leave the hospital.

You can be released from the hospital after recovery.

应用解析：

You may depend upon it.

肯定无疑，放心好了。

3. Can you tell me why I can't be discharged now?

你能告知我现在为什么不能出院吗？

还能这样说：

Will you please tell me the reason why I can't be released from the hospital?

Could you tell me the reason why I can't leave the hospital?

应用解析：

discharge a gun 开炮；

discharge one's pistol in the air 假打，佯击；

discharge sb. from an obligation 免除某人的义务；

bad conduct discharge 撤销军职

4. You are going to be discharged tomorrow.

您明天就可以出院了。

还能这样说：

You are allowed to be discharged from hospital tomorrow.

You will be discharged from hospital tomorrow.