def sums(num):

    global s

    s = 0

    s = s + num

sums(5)

def myfun(___):

       pass

def myfun(x,y,z)

    return x+y*z

下列语句能正确调用该函数的是？（ ）

def tree(n):

    if n == 1:

        return 1

    else:

        return _______________

def gcd(a, b):

    if a % b == 0:

        return b

    return gcd(b, a % b)

print(gcd(168, 66))

def fun(n):

    if n in (1, 2):

        return n

    f1, f2, res = 1, 2, 0

    for i in range(3, n+1):

        __________

    return res