1a. 帆船沿着 ‘之’形路线，左右迂回前进。
Fānchuán yánzhe ‘zhī ’ xíng lùxiànzuǒ yòu yūhuí qiánjìn.
(The sail boat, along a route with the shape of the character ‘之’, sailed circuitously.)
Qízhōng wǔ kē dà xīng cháozhe yī gè fāngxiàng yùndòng.
(Among them there are five big stars moving in one direction.)
Wèile qūsàn wéiguān de rénqún，jǐngchá cháo tiān fàng le yī qiāng.
(The policeman shot once towards the sky to dispel the crowd that was surrounding and watching.)
Tā wǎng shānxià de xiǎoxuéxiào zǒuqù.
(He walked down the hill toward the primary school.)
The direction adverbials 朝着一个方向‘cháozhe yī gè fāngxiàng’ (towards the same direction), 朝天‘cháotiān’ (towards the sky) and 往山下‘wǎng shānxià’ (towards the foot of the hill) describe the direction of the actions denoted by the verbs. Before the initiation of an action, a direction involved in the action must be taken and maintained during the process of the action. Assuming a direction and maintaining the direction represents a state, the state obtains before the action and continues with the action. Therefore, they are ordered before the verbs in terms of the PTS. In (1a), the prepositional phrase 沿着‘yánzhe…’ (along) signals the route or course of the action of sailing, the course is maintained during the whole process of the action. Hence the adverbial is ordered before the VP 前进‘qiánjìn’ (advance, go forward).
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.