Complete the sentence with the correct words considering what you learned in lesson 7 - Past Perfect Continuous and Present Perfect Continuous.
The poet _______ romantic poems _______ morning.
a. had been writing / until
b. had been writing / for
c. had been writing / since
The correct completion of the sentence is:
b. had been writing / for
So the complete sentence would be: "The poet had been writing romantic poems for morning."
However, please note that the phrase "for morning" might not be the most natural expression. It would typically be more appropriate to say "The poet had been writing romantic poems for hours" or "The poet had been writing romantic poems since morning."