A literary or cinematic genre in which fantasy, typically based on speculative scientific discoveries or developments, environmental changes, space travel, or life on other planets, forms part of the plot or background.科学幻想：一种文学或影视类型，典型地以推测性的科学发现或发展、环境变化、空间旅行或其它星球生命体等幻想为基础构成情节部分或背景