According to the passage, which aspect of skyscrapers were some residents of North America concerned with in the late 1960's?

• A、The poor reception of radio and TV signals.
  
  

• B、The removal of trees and grass from building sites.
  
  

• C、The harmful effects on the city's plans.
  
  

• D、The obstruction of air traffic
  
  

Which of the following is true according to the passage?

• A、Skyscrapers provide more usable space than other buildings.
  
  

• B、The skyscrapers first appeared in the late 1960's.
  
  

• C、Where there are skyscrapers, television reception is poor.
  
  

• D、The two World Trade Center towers are skyscrapers.
  
  

Task 1

16.Paragraph     ①     

17.Paragraph     ②          

18.Paragraph     ③      

19.Paragraph     ④           

20.Paragraph      ⑤      

A.Education

B.Land and Climate

C.State System

D.General Introduction

E.Economy

F.Population