Choice of Words: Keys are small objects used to open locks. Door is a large object that allows people to enter or leave a building or room. Open means to make something accessible by moving a barrier.
Alternative Expressions
The key unlocks the door.
Meaning: This sentence is similar to the first one, but it emphasizes that a specific key is used to open a specific door.
Choice of Words: The word "key" is singular, referring to a specific key. "Unlocks" means to open something that is locked. "Door" is the same as in the previous example.
Using the key, the door can be opened.
Meaning: This sentence explains that the key is essential for opening the door and that the door can be successfully opened when the key is used.
Choice of Words: The word "using" indicates that the key is necessary for the action of opening the door. "Can be opened" means that it is possible to open the door with the key.