粵語作為一個VO語言有着[PP V]而不是[V PP]作為主要語序是不尋常的。Dryer (1992) 發現VO語序跟[V PP]語序有着很強的相關性。Hawkins (1994) 提出一個解釋，就是VO語言跟[V [PP P NP]] 語序有着最理想的處理效率。本篇文章研究為何儘管[PP V] 有着較低的處理效率，粵語仍然使用[PP V]語序。粵語中的[[PP P NP] V]語序符合象似性原則, 但有着較低的處理效率。根據Hawkins (1994) Early Immediate Constituents (EIC) 的量度方法，話題介詞短語結構(topic PP construction)比[[PP P NP] V] 有更高的處理效率，話題介詞短語結構能作避免低處理效率的[[PP P NP] V] 的一個途徑。語料庫的資料顯示，當介詞短語越長，它出現在話題位置的百分比就越高。本文論証話題介詞短語結構皆符合象似性原則和處理效率的原則，話題介詞短語結構顯示兩個似乎是處於競爭狀態的功能動因(象似性原則和處理效率的原則)能夠彼此相容。

Cantonese is unusual as a VO language in having [PP V] as the dominant order instead of [V PP]. Dryer (1992) found that VO order correlates strongly with [V PP] order. Hawkins (1994) offered an explanation in arguing that VO language and [V [PP P NP]] order can be processed with optimal processing efficiency. This paper investigates the reasons why Cantonese still employs the [PP V] order despite its lower processing efficiency. While [[PP P NP] V] order in Cantonese conforms to iconicity, the inefficiency of the [[PP P NP] V] order is circumvented due to the availability of the topic PP construction, which is shown to have higher processing efficiency when compared to [[PP P NP] V] by Hawkins‟ (1994) metric of Early Immediate Constituents (EIC). Corpus findings show that the heavier the PP, the larger the percentage appearing in topic position. As I will argue, the topic PP construction which exhibits both iconicity and processing efficiency shows that the two seemingly competing functional motivations, iconicity and processing are compatible with each other.