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My Sudo is not working. I am a new Ubuntu user. Please help me. What is error in my sudo? How can I slove it? Here I am typing my error:

N: Ignoring file 'some-ppa.listM-M' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Type 'sudo' is not known on line 1 in source list /etc/apt/sources.list.d/mono-xamarin.list
E: The list of sources could not be read.
N: Ignoring file 'some-ppa.listM-M' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Type 'sudo' is not known on line 1 in source list /etc/apt/sources.list.d/mono-xamarin.list
E: The list of sources could not be read.

Please help me. How can I solve it?

marked as duplicate by steeldriver, karel, user535733, Fabby, Thomas Dec 2 '18 at 11:24

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