Holonyak's colleagues thought he would fail in his research on LEDs at the time when he started it.

• A、True
  
  

• B、False
  
  

• C、Not Given
  
  

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

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.