Here are the corrections needed for each question based on the underlined parts:

**Question 23:** **C** should be corrected to "had" to "has" (My mum asked me if I have had my ear pierced).

**Question 24:** **C** should be corrected to "are" to "were" (Fiona asked Rod and Jenny whether they were still moving to Blackpool).

**Question 25:** **A** should be corrected to "what was" to "what is" (He asked her what is the difference between a refugee and an asylum seeker).

**Question 26:** **C** should be corrected to "was" to "be" (Carl asked Megan who she was with the weekend before).

**Question 27:** **B** should be corrected to "was" to "is" (I replied going swimming in such cold water is a ridiculous idea).

**Question 28:** **A** should be corrected to "will be" to "would be" (the Prime Minister stated that his government would be corruption-free).

**Question 29:** **A** should be corrected to "always" to "used to" (my English teacher used to tell us that we didn’t have to pay attention).

**Question 30:** **C** should be corrected to "shall" to "would" (that they would be in touch again).

This identifies the issues present in the underlined sections of the sentences.