This is the 7073rd most frequent Chinese word.
直升机
Helicopter.
In this sentence, '直升机' is used as the subject noun referring to a specific helicopter.
这架直升机飞得很高。
This helicopter is flying very high.
Here, '直升机' serves as the object noun and specifies the mode of transportation.
我们准备坐直升机去山顶。
We are planning to take a helicopter to the mountaintop.
In this instance, '直升机' is used as a possessive noun indicating the entity being described.