We use the _____ to go up and down the tall building.空内应填elevator还是elevators?

We use the _____ to go up and down the tall building.空内应填elevator还是elevators?
We use the _____ to go up and down the tall building.空内应填elevator还是elevators?

We use the _____ to go up and down the tall building.空内应填elevator还是elevators?
前面有THE 用elevator 特指

elevator.电梯，这里强调的是工具，并不是数量