Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: The nuclear envelope is a double-layered plasma membrane like the cell membrane, although without membrane proteins.

Output: The nuclear envelope is a double-layered plasma membrane like the cell membrane, although without what?


Input: Consider Input: Elements are pure substances that make up all matter.

Output: Elements are pure substances that make up what?


Input: Consider Input: Charophytes are the closest living relations to land plants.


Output: Which are the closest living relations to land plants?