Question

This building...built by next month 1will built 2will have built 3will have been built 4will be building

Answer 1

This building will have been built by next month 
Future Perfect, т.к. будет построено к определенному моменту.
+старадательный залог, действие над объектом совершается: to be+3 форма глагола

will+have+to be+3 форма глагола

Answer 2

The correct option is:

3. will have been built

The correct sentence is: "This building will have been built by next month."

Option 1 ("will built") is grammatically incorrect because the correct future tense form of "build" is "will build."

Option 2 ("will have built") is grammatically correct but does not convey the same meaning as the original sentence. It implies that someone or something will finish building the building by next month.

Option 3 ("will have been built") is the correct choice as it indicates that the building will be completed and ready for use by next month.

Option 4 ("will be building") suggests that the building's construction will be in progress by next month, but it may not be completed by then.