There is not much the airlines can do when it comes to      (  ).

• A、making sure. the departures are not delayed
• B、the efficient handing procedure
• C、speeding up customs procedure
• D、the improvement of the condition of waiting lounges

16. Paragraph➊17. Paragraph❷

18. Paragraph❸

19. Paragraph❹

20. Paragraph❺

A. Main Results of Recent Researches

B. Difference between Genetic and Observed Intelligence

C. Effect of Environment on Intelligence

D. Intelligence and Achievement

E. Impact on School Education

F. A Changed View of Intelligence

According to the passage, in operating airlines it is essential to     .(  )

• A、keep in mind the need. of the executives only
• B、satisfy the need of the low fare passengers at the expense of the executives
• C、try to attract as many passengers as possible by reducing fares
• D、cater to the need of passengers setting at both ends of the jets