Sure, I'd be happy to help you with that. Let's go through each sentence and identify the mistakes in the underlined parts: Question 41: The mistake is in part A. The correct sentence should be "I asked him how far it was to the station if I went there by taxi." The word order of the question is incorrect. Question 42: The mistake is in part B. The correct sentence should be "Although he was tired, he still went to work yesterday." The conjunction "but" is unnecessary after "although." Question 43: The mistake is in part C. The correct sentence should be "My family spent an interesting holiday in Europe last summer." The adjective "interested" should be replaced with "interesting." Question 44: The mistake is in part C. The correct sentence should be "The children laughed happily while they were playing with their toys." The adverb "happy" should be replaced with "happily." Question 45: The mistake is in part A. The correct sentence should be "I still have to finish my project, which keeps me very busy." The conjunction "what" should be replaced with "which." I hope this helps! Let me know if you have any other questions or need further assistance.