8-1条件语句。
#statement A
if x > 0:
#statement B
pass
elif x < 0:
#statement C
pass
else:
#statement D
pass
#statement E#statement A
if x > 0:
#stat8-1条件语句。
#statement A
if x > 0:
#statement B
pass
elif x < 0:
#statement C
pass
else:
#statement D
pass
#statement E#statement A
if x > 0:
#stat