This study investigates the effects of working memory capacity (WMC) and the types of vocabulary learning, i.e., explicit vs. implicit, on the acquisition of English multi-word verbs. For this purpose, a total of 60 middle school students, divided into two groups (control and experimental), participated in the study. The participants in the control group were taught multi-word verbs in a traditional and explicit manner, whereas the participants in the experimental group were exposed to multi-word verbs with short passages. The results manifested that both of the instructional styles had positive effects on the learners’ acquisition of multi-word verbs in the short-term. Although there was not a significant interaction between WMC and the overall scores on the immediate post-test, according to the scores on the gap-fill tasks which tested learners’ productive knowledge, there were significant differences between the low-WMC and high-WMC groups. High-WMC students learned more target multi-word verbs than low-WMC students on average. The results also showed that WMC and the two different learning types did not affect the students’ acquisition of multi-word verbs in the long-term. Further, the interaction effect between WMC and learning type in the long-term was not significant.

Some multiword verbs like run into ‘encounter’ in She ran into a friend have been called by two distinct names in the literature. They are prepositional verbs (with a fixed and specified preposition) or (inseparable or nonseparable) transitive phrasal verbs. This paper argues that this different use of terminology for the same multiword verbs actually reveals the nature of the whole class they belong to. The class is a cline of grammatical elements and properties between prepositional verbs and transitive phrasal verbs, and the set shared by these two subclasses is the locus of that cline. This characteristic mode of the cline is explained in terms of intersective constructional gradience and multiple inheritance.