AttributeError: 'Enemy' object has no attribute 'blit'

Question

I am making a spaceship game where you control a spaceship and fire bullets to defeat enemies. However, when I run my game, I get this:

Traceback (most recent call last):
File "C:/eqodqfe/t2.py", line 98, in enemies.draw(enemy)
File "C:\Users\linpang2018\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pygame\sprite.py", line 474, in drawsurface_blit = surface.blit
AttributeError: 'Enemy' object has no attribute 'blit'

Why does this happen? How do I fix it? This is my current code: (Some parts omitted or replaced by --snip--)

class Spaceship(pygame.sprite.Sprite):
    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen = s
        self.x, self.y = x, y
        self.image = pygame.image.load("C:/eqodqfe/spaceship.png")
        self.image = pygame.transform.scale(self.image, (175, 175))
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


class Bullet(pygame.sprite.Sprite):
    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        --snip--

    def update(self):
        self.y -= 5
        self.rect.center = (self.x, self.y)
        if self.y < 0:
            self.kill()


class Enemy(pygame.sprite.Sprite):
    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen, self.x, self.y = s, x ,y
        self.image = pygame.image.load("C:/eqodqfe/enemy.png")
        self.image = pygame.transform.scale(self.image, (240, 210))
        self.rect = self.image.get_rect()
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


spaceship = Spaceship(screen, 400, 400)

bullets = pygame.sprite.Group()
enemies = pygame.sprite.Group()

clock = pygame.time.Clock()

running = True
while running:
    --snip--  # (event loop and spawning bullets)

    bullets.update()

    key = pygame.key.get_pressed()
    amount = 5

    if key[pygame.K_a]:
        spaceship.x -= amount
    --snip--

    spaceship.update()

    screen.fill((255, 255, 255))

    screen.blit(spaceship.image, spaceship.rect)

    enemy = Enemy(screen, randint(-200, 800), -100)
    enemies.add(enemy)

    bullets.draw(screen)
    enemies.draw(enemy)

    pygame.display.update()
    clock.tick(60)

Answer 1

pygame.sprite.Group() works like this:

Draws the contained Sprites to the Surface argument.

So the line

enemies.draw(enemy) 

should be

enemies.draw(screen)

as the argument has to be a Surface, not a Sprite.