Chinese directional complements.
Hello

I am currently studying "chinese directional complements". I already understand it's usage but still have some questions about it:

1 - What is exactly a "directional complement"?
Cause some grammar books say they are 去 and 来, other say they are "direction verbs" as 上,下, 回, 过, 进, 出... some say the combination of both...

2 - If I wanted to say, "He got on the plane" Which expressión is better? What are the differences between them?

1. 他走上了飞机。
2. 他上去了飞机。
3. 他走上飞机去了。

3 - If I wanted to say, "Please walk in" Which expressión is better? What are the differences between them?

1. 请，走进。
2. 请，进走。
3. 请，走进去。

Thanks to all in advance :-)

Alberto

Question

Chinese directional complements.
Hello

I am currently studying "chinese directional complements". I already understand it's usage but still have some questions about it:

1 - What is exactly a "directional complement"?
Cause some grammar books say they are 去 and 来, other say they are "direction verbs" as 上,下, 回, 过, 进, 出... some say the combination of both...

2 - If I wanted to say, "He got on the plane" Which expressión is better? What are the differences between them?

1. 他走上了飞机。
2. 他上去了飞机。
3. 他走上飞机去了。

3 - If I wanted to say, "Please walk in"  Which expressión is better? What are the differences between them?

1. 请，走进。
2. 请，进走。
3. 请， 走进去。

Thanks to all in advance :-)

Alberto

Answer

All the solutions you mentioned are good and correct. But maybe you can try neater ones, like this: 
He got on the plane. 他上飞机了 / 他登机了。
Please walk in. 请进。

I think directional complements in Chinese work the same as in English, like come and go. Only we added more direction words which can also be used as verbs. In theory it sounds complicated, but in using it's actually making the sentence shorter and easier.

Answer

1 He got on the plane 他上了飞机 this scentence foucus on "got already" your three scentence foucus on the behavior，that will be different.
2 Please walk in 请进 if you wangt to say "come in" 请进will be local than ever.If a policeman said"walk in" He could emphasis you to walk rather than jump
Tip: you should know what kinds of action you want to say or let others do! grammar is not always help you sometime,do not always foucus on grammar

Answer

I see Wei, very nice explanation. So, the use of verb of movement + directional complements is not obligatory (走上， for example) unless you want to leave clear the kind of movement (run, walk, swim...)

And the use of 去 or 来  is not obligatory either unless you want to leave clear the perspective of the speaker. Is that correct?

Instead of saying 他走上飞机去了。
I can simply say 他上飞机了。

Is that correct?

You can use just a single verb to say the same, can't you?

Answer

1.他走上了飞机 => it emphasizes he was "walking" into the plane. 
2.他上去了飞机 => it means he already on the plane . or we say 他上飞机了. 他在飞机上了. 
3.他走上飞机去了 it is similar to sentence 1. more colloquial saying. for example, you can say 他回家了 or 他回家去了. Which expression is better? I would like to say 他上飞机了 or 他在飞机上了.
the final question , we say 请走进去! or just say 请进!  we don't say 请走进 because it sounds like you didn't finish your conversation, you need to add object in the end. for example : 请走进房間. and we don't  say 请进走 too, it is completely wrong.

Answer

他走上了飞机 =>  it emphasizes he was "walking" into the plane.

他上去了飞机 => it means he already on the plane .
or we say 他上飞机了. 他在飞机上了.

他走上飞机去了 it is similar to sentence 1. more colloquial saying.
for example, you can say 他回家了 or  他回家去了

Which expression is better?  I would like to say 他上飞机了 or 他在飞机上了.