yi…Jiu…(as soon as)
>> ni(you) yi(~ once)Dao Zheli(get here), wanFan(dinner/supper) Jiu(~ soon) maShang(at once) Zuo hao(get ready).
[yi + condition + Jiu + result]
In the example above, the condition is [you get here], it is put after the word [yi], and the result is [dinner will be ready.]
The condition and result are both separate sentences. However the subject is [Dinner], not [you]. You is just part of a conditional clause functioning as an adverbial modifier.
We can also say like this:
yiDan(once) ni(you) Dao(arrive) Zheli(here), wanFan(dinner/supper) Jiu(~will soon) maShang(in no time) Zuo hao(be ready).
>> NaGe(That) xiaotou(theft) yi(just) Zai jieShang(in the street) Xianshen(show up), jingcha(police) Jiu(~soon) ba ta(get him) zhuaZhule(arrested/grabbed).
Here, the pattern is
clause subject + yi + condition, subject + Jiu + result.
Give this wallet back to the customer.
>> ba this wallet given back to the customer.
>> (ba ZheGe qianbao[this wallet] geihui[give back] GuKe[customer].)
The word ba is a preposition, its second meaning is a verb: to grab.
>> give me(gei wo) the pen(bi), I will(wo lai) draw(Hua) a map(yi zhang Ditu) for you(gei ni).
Note that [for you] may be located ahead of the verb draw as well, where it will be a typical adverbial modifier. While in the sentence above [for you] is a complement.
This street trader was really frightened by the local subpolice.
[This statement may sound wield for most of you. And you may be confused about the word subpolice. It actually describes a very serious and common tension between the police and people in modern China. The subpolice are a subdivision of the police, they are hired by the police to take care of some nasty street order controlling jobs, including getting rid of street traders to make the city look nicer. You may think this kind of information is irrelevant to what we are learning. If you are planning to travel in China, you may think otherwise. If you want to communicate with locals, understanding their environments, their words is important.]
How do we say this sentence then?
ZheGe jieDao xiaoFan Bei chengguan XiaHuaile.
>> This[ZheGe] street trader[jieDao xiaoFan] by[Bei] the subpolice[chengguan] scared to death[XiaHuaile].
English-like pinyin: DserGher jayDao shyaoFan Bay tsenggwan SharHwhy le.
>> laoshu(rat) Zai chufang(in the kitchen) Bei (by) hei mao(black cat) gei[~helps to indicate a passive voice] daiZhu(catch)le[-ed].
About the preposition [gei], it can be omitted, actually.