The correct modal to fill in the blank is OPTION 2 - would be
The complete sentence would be: We would be flying to Moscow now if we had bought tickets in time.
Would be indicates a present conditional situation, which fits the context of something that could be happening now if a past condition (buying tickets) had been met.
Should have been and must have been refer to past events, which don't match the present situation.
Need to be does not express the hypothetical nature of the sentence. |
