I could show you his house if you would permit me. As examples of the language, i have decided to use two totally different sources of text. The book uses american english.
The seashell was found by the girl in the white hat. Be is added after modal and past participle follows after it. We may ask him a few questions. Affirmative sentence 2 subiect modal auxiliarv not be past participle. In this example, it is not so important who built the house. Shall used in question forms usually.
Negative sentence 3 modal auxiliary subiect be past participle. They are called modal auxiliaries and are followed by the infinitive without to. I can't identify very well if this estructure is used in present or past sentences. We typically use active voice, where the subject of the sentence is the person or thing performing the action.