A. occurs most infrequentlyB. is shifted sideways by strong windsC. is often hidden from o
A. occurs most infrequently
B. is shifted sideways by strong winds
C. is often hidden from our view
D. is equipped with a good knowledge of various forms of lightening
E. is estimated at 20 millions a year
F. is positively charged
In most cases of cloud-to-ground lightening, the ground's surface ______.