Here's the completed text using the correct forms of the verb "to go":
(a) We usually go to the mountains on holiday.
(b) Last year, we went to the Pyrenees.
(c) My cousin always goes to the US.
(d) She went to New York, Washington and Boston.
(e) Her favourite place was New York. She didn't go on holiday last year, but she
(f) is going to San Francisco next year.