Помогите,пожалуйста.Необходимо раскрыть скобки:When the Director of the Hermitage (to ask) how

Помогите,пожалуйста.
Необходимо раскрыть скобки:
When the Director of the Hermitage (to ask) how the Museum (to
get) such a big collection, he (to answer):
The history of our Museum (to begin) in 1764 when 225 paintings
(to purchase) in the West by Catherine the Great. The collection (to grow)
in size from year to year since then. After the revolution a lot of splendid
pieces of art (to come) to the Museum from private collections.