Title: Nanjing.
Question: How many days of rain does Nanjing get a year, on average?

Title: Financial crisis of 2007%E2%80%9308.
Question: Who made the decision to seize Countrywide after their financial condition deteriorated?

Title: Iran.
Question: What resulted from the Persian Revolt?

Title: Railway electrification system.
Question:
What issue can complicate electric railway service?