• A. can be found in Paris
• B. the major events of the nation
• C. of the country’s industries
• D. a lot of cinemas and theatres
• E. has been growing steadily
• F. has been decreasing rapidly

Paris has in history been the center of______.

A．child maltreatment is a global problem
B．there is no exact data about low-and mid-income countries
C．there is a shortage of the professional data collectors
D．different scientists use different research methods