Using the information in the text, complete each sentence 14-18, with a word or phrase from the list below.
For each sentence(14-18), mark one letter(A~G)on the Answer Sheet.
Do not mark any letter twice.
A. copy
B. a positive charge
C. a negative charge
D. super cooled clouds
E. falling hail clouds
F. hail and super cooled clouds
G. moisture particles

填空题 According to Dr. Score , lightning is caused by hail falling through 1.

填空题 The refrigerated rod served the same functions as 1.

填空题 Ice particles bouncing off hail falling through a cloud acquire 1.

填空题 In the paragraph four the word "duplicated" means 1.

填空题 According to S.E. Regnolds, there could be no lightning without 1.