Translation:If it rains tomorrow, then we won't go out.
"If it rains tomorrow, then we won't go out" should also be accepted, as "If... then..." is a common sentence construction in English
Same problem here. And I think the use of 就 sort of conveys this meaning anyway.
This should also accept "If it rains tomorrow we just won't go out". That's natural in English and covers the 就.
The character for 'then' appears in the Chinese text. It should be accepted in the English response.
"If it rains tomorrow, then we will not go out" should also be accepted as answer
They should allow it as correct with or without "then". Translating literally word by word won't get us that far in learning Chinese. We also have to learn when and where to be flexible.