An appropriate title for this passage would be__________.

单项选择题One implication of the final sentence in the passage is that_________

单项选择题The author's definition suggests that all science fiction deals with_________

单项选择题The view of science fiction encouraged by pulp magazines, which may be wrong, is nevertheless__________.

单项选择题Which of the following does not usually contribute to the theme in a piece of science fiction

单项选择题Science fiction is called a literary sub-genre because__________.