English has two major future tense constructions, will and be going to. Additionally, English can also use the present tense with a future-marking adverbial to express futurity. However, the distributions of these future markers are not free but limited. Instead of discriminating the differences among these distributions through direct comparison to etymological meanings or intuitive examples, this study offers an account for the semantic and syntactic differences between the two major English future tense constructions by analyzing data retrieved from the British National Corpus (BNC). The focus of attention is chiefly on the semantic and syntactic differences that lead to the choices British English native speakers make when expressing futurity. Based on the empirical analysis of data from the BNC, this study demonstrates that distribution of the future tense constructions seems sensitive to the following factors: (1) event-time orientation (temporal posteriority) or present-time orientation (prospective aspect), (2) the levels of verbal dynamicity in the whole sentence, (3) contexts of subordination, and (4) different text categories. The analysis suggests that the futurity constructions are not in the same distribution but are semantically and syntactically different. Utilizing its findings, this study aims to enhance second language learners’ expression of futurity by providing pedagogical suggestions.

英語有兩種主要的未來式結構，分別是「will」和「be going to」。此外，英語還可以使用現在式搭配未來標記的副詞來表達未來。然而，這些未來標記的分佈並不是自由的，而是有限制的。本研究並不是通過直接比較詞源意義或直覺例子來區別這些分佈之間的差異，而是通過分析從英國國家語料庫 British National Corpus（BNC）檢索到的數據，對英語兩個主要未來式結構之間的語意和句法差異進行解釋。重點關注的是在表達未來時，以英語為母語的英國人所做的選擇所導致的語意和句法差異。通過對 BNC 數據的實證分析，本研究表明，未來式結構的分佈取決於以下因素：（1）事件-時間取向（時間後驗）或現在-時間取向（未來面向），（2）整個句子中動詞動態性的水平，（3）從屬的上下文，以及（4）不同的文本類別。分析表明，未來式結構的分佈並不相同，而在語意上和句法上有所不同。本研究旨在通過本研究的發現提供教學建議來增強第二語言學習者對未來式的表達能力。