In Modals^x, Colons^x, Tenses^x

Hello, this is my first post here, I like to know these words kilometer centimeter Are those words noun if they are standing alone ? if it's, what kind of noun it's, proper noun or abstract noun or etc ? After that, I want to indentify the part of speech of the following sentence by using the...

Hi, 1. You will not have heard of me before but I used to live next door to your sister. 2. That is absurd; they really could not have taken your motorbike by mistake, surely ? 3. You are a bit overweight; you should have been doing more regular exercise. 4. You were to have been promoted....