Several English multiple-choice questions in grade three

Choose B for the first question. The most important thing in doing English questions is to divide sentence components. The so-called sentence elements are nothing more than the main system table, subject-predicate object and so on. All right! Let's divide the first question into several parts, that is, the photos are on display. Obviously this is a sentence from the main system table?

The theme is photos. What kind of photo is it? Obviously, this was taken by the photographer, and the photographer took it to decorate the photo.

Choose B for the second question.

It doesn't matter. It's a complete sentence, followed by you. That seems to be a common choice, but the sentences after that are obviously not translated smoothly. Is it more reasonable to bring in if and translate it into sentences?

The third one is definitely not appositive, and neither is the attribute. I don't know what this clause is.