I guess you meant the following:
'In C language, when you call a function,the parameters are passed by-value.'
Any experssion including assignment or a function call can be a statement in C
Functions in C language may call themselves (ie can be recursive) without restrictions.
Not possible. Of course you can call a function which does the addition for you, but function-calling is also an operator in C.
A subroutine is a procedure call. In other words, a function call.
The c language does not have template functions. That is a c++ thing.
libray in c++
The hearing rods for identifier "c" language is the function.
Nothing.
No.
'Clearscreen' is not used in C language. TurboC has a clrscr function (prototype in conio.h).
C language uses only one method for parameter-passing: call by value.
No. At minimum, you need to provide a main() function.