本文以最简方案为理论框架,以对比分析和图示的方式对标句词that、if和for进行深入探讨。属于功能性语类的标句词可以分为限定性标句词和非限定性标句词,且在句子结构中标句词既可呈显性形态也可呈隐性形态。最简方案下的标句词在句法结构中扮演重要角色,它作为中心语可以投射出句子的最大结构CP。 This article takes the simplest plan as the theoretical framework, and conducts an in-depth discussion on the predicate terms, if and for using comparative analysis and illustration. Sentences belonging to the functional category can be divided into two types: the definite sentence and the unqualified one. In the sentence structure, the target sentence can be both dominant and recessive. Sentences under the Minimalist Scheme play an important role in the syntactic structure. As the central language, the target sentence can project the largest structure CP of a sentence.