If you shouldn't mind me to ask where you are going when me and my sister’s seen you last week as you had been getting on bus on the Main street.
1. Question form: use “do” as the auxiliary verb to make a negative question (…don’t mind …).
2. Infinitive/Gerund: After the verb “mind” use the gerund (asking) not the infinitive.
3. Verb tense/question form: The questions is about something that happened in the past, so use the past progressive tense instead of the present progressive. Because this is a question and not a statement, the word order needs to reflect that (were you going).
4. Pronoun usage: “me” is an object pronoun, but the verb “see” requires a subject--“I” is the subject pronoun.
5. Verb tense: “Seen” is the past participle; it is used to help make the perfect tense or the passive voice. Here, we need the simple past “saw”.
6. Verb tense: “had been getting on” use the past perfect progressive tense, but there is not reference to another time in the past, so use the past progressive tense (were getting on).
7. Article usage: We need to specify “bus”; here because it is not any specific bus, it is better to “a”. However, we don’t use articles with streets, so omit “the”, but see point 9 for more information
8. Capitalization: Either use all capitals (Main Street) if that is the name of the street; however, if it’s not the proper name of the street, then you do need the article “the” before “main street”.
9. Punctuation: There are three important situations here: 1) After an “if” clause (conditional clause) use a comma--place after “asking”; 2) This whole sentence is an example of direct speech; as a result quotation marks are needed. 3) The sentence is a question, so use a question mark.
Sample Answer: “If you don’t mind me asking, where were you going when I and my sister saw you last week as you were getting on a bus on Main Street?”