The subject-verb agreement is tricky in a sentence or dependent clause that begins with the words "there, that, which, who," or "what" because they are not real subjects to determine agreement. You ...
This clip is from the series Grammar for ... sentences replacing common verbs with more adventurous and interesting ones. This clip is suitable for teaching English at Key Stage 3 or Third Level.
There is a misconception that all verbs in a paragraph should be in the same tense. The choice of the appropriate verb tense depends on context and meaning.