This type of sentence structures renders the adverbials in the form of a NP with a relative clause marked by an adverbial connector, typically used to indicate time [d¯ang (當)/z`ai (在) . . . de sh´ıh`ou (的時候) "when"], [d¯ang (當)/z`ai (在) . . . y˘ıqi´an (以前) "before"], [d¯ang (當)/z`ai (在) . . . y˘ıh`ou (以後) "after"], as well as conditionals [r´ugu˘o (如果)/ji˘ar´u (假如)/zh˘ıy`ao (只要) . . . de hu`a (的話) "if"].
The adverbial connectors such as d¯ang (當) and z`ai (在) at the beginning of the clause can be deleted.
(d¯ang) w˘o hu´ı ji¯a de sh´ıh`ou, l`u-sh`ang ch¯u-le ch¯e-hu`o
When I returned home, (there was) a traffic accident on the road.
(z`ai) w˘o hu´ı y˘ıh`ou l`u-sh`ang ch¯u-le ch¯e-hu`
After I returned home, (there was) a car accident on the road.
ji˘ar´u w˘o hu´ı ji¯a de hu`a, n˘ı ji`u h`ui b`u h˘ao-h˘ao
If I went home, you would not work very hard.
Reference: Chinese: a linguistic introduction by Chao Fen Sun