1) The document discusses how verb tenses change when direct speech is reported as indirect speech, such as changing from present to past tense.
2) It also explains how modal verbs like "will" and "may" often change to "would" and "could" respectively in indirect speech.
3) However, some modal verbs like "should", "could", "might", and "ought to" do not change in indirect speech, nor do verbs in past perfect tense, present or past unreal conditionals, or past modal verbs.