1)I won't buy a souvenir if the shop is closed next Wednesday. 2 вариант
2) They will visit London Eye if she comes to london next week. 4 вариант
3) if people stop throwing rubbish into the local river, clean water won't be a problem in this city. 3 вариант
4) sam meet you if you will be here tomorrow. 1 вариант
5) if Tom and Jerry clean up after a picnic with their friends, Ann will invite them to the party next Friday. 1вариант
6) will you go if tom invite you?