Mr golovin got an invitation letter yesterday . ( mr wooding will phone mr golovin tomorrow. ( a group of 20 russian students can come to london.(how составить вопрос надо

Mr Golovin got an invitation letter yesterday . (What did Mr Golovin get yesterday?)
Mr Wooding will phone  Mr Golovin tomorrow. (When will Mr Wooding phone  Mr Golovin?)
A group of 20 Russian students can come to London.(How many Russian students can come to London?)