Can you tell me if that is true?if 前是否省略了that?

Can you tell me if that is true?if 前是否省略了that?
Can you tell me if that is true?
if 前是否省略了that?
tell sb 后面一般不是跟that
我也知道if 可以引导宾语从句，
只是 我看到 前面是 tell sb 因为看tell sb that 从句见得比较多。所以才这么问。