R: characters

hi all 

assume that i have the following table

a=rbind(c(T,T,F),c(F,F,T))

a

[,1]  [,2]  [,3]
[1,]  TRUE  TRUE FALSE
[2,] FALSE FALSE  TRUE

I would like to change all the FALSE entries to a blank. how can i do
this?

i could simply use

a[a==F]=""
a

but then how would i remove the " " from the entries.

i know that this should be very easy!!!

/
allan