Perhaps the biggest problem with understanding long sentences is that they seem to be a lot longer than the basic syntax unit. Today we accept that there are seven basic sentence pattern types, where the possible number of obligatory units is between 2 and 4 (SVOC, SVOO and SVOA). Yet a sentence with, for example, eleven words seem difficult to fit into this pattern. The secret is to chunk them into units. Take the following sentence:
A lot of Carp fans are standing by the back entrance.
What is the subject? We know the subject of a sentence is a person (who) or a thing (what). And that in this case “standing” implies a person or people. So ask the question:
Who is (or who are) standing by the back entrance?
The answer is of course Carp fans. If in doubt the entire chunk ‘a lot of Carp fans’ would also be fine to be called the subject.
Incidentally, if you want to know what is the pattern type just think about what is necessary within the sentence.
In the above sentence almost every word is necessary. The only words which can be cut are ‘a lot of’, ‘Carp’ and ‘back’ which gives us
Fans are standing by the entrance.
Words which help nouns are called ‘adjectives’ and are mostly “decorative”. The remainder of the sentence therefore tells all that we need to know, that there are fans and they are standing (implying waiting) by the entrance. This is an SVA sentence. You can say
The fans are standing. △
but that would have a different meaning not implying waiting. Therefore by the entrance is obligatory.