Problem: How does the sentence end?

Michael put more effort into their relationship than Jason, because 
Answer: Michael was more invested in its success.

Problem: How does the sentence end?

John used the megaphone instead of the microphone to amplify his voice. The 
Answer: microphone was quieter.

Problem: How does the sentence end?

He tried to put the iron in the box but the 
Answer: iron was too big.

Problem: How does the sentence end?

During the recording session the artist didn't make a sound out of the drum but instead used the flute because the 
Answer:
drum was broken.