Помогите по английскому языку White correct sentences 1)If they ______ the

Помогите по британскому языку
White correct sentences
1)If they ______ the fountains in Rome,they _____ them . (see,enjoy)
2)What /How long the Nile rives is!
3)If you ____ to London you ____ the spectacular sights of this ancient country. (go,see)
4)It is not easy cross ____ Atlantic Ocean in _____ small boat (a,an, the,---)