Continuity question!! hellpppp!

GIVEN THESE PIECE-WISE FUNCTIONS

f(x) = {1 , if 0≤x
0 , if x<0

and

g(x) = {0 , if 0≤x
1 , if x<0

i have to find if these functions are continuous at x=0 in each of these parts:

f(x)
g(x)
f(-x)
lg(x)l
f(x)g(x)
g(f(x))
f(x) + g(x)

how do you do this???

no , no , no , no , yes , yes, yes..use the knowledge of continuity and limits

left limit = right limit = function value at the limit point