Problem: How does the sentence end?

Doug had a lot of pain in his knee even after his shoulder was completely healed, because the 
Answer: knee was weaker.

Problem: How does the sentence end?

Sarah encouraged Carrie to be more subtle in her movements, because 
Answer: Carrie is her student.

Problem: How does the sentence end?

Sally knew not to ask the doctor for antibiotics when her illness was caused by a virus rather than bacteria. The 
Answer: virus wouldn't respond to antibiotics.

Problem: How does the sentence end?

Patricia went to the bird cage in the zoo before Monica did although 
Answer:
Monica owned several birds themselves.