1. 研究目的与意义（文献综述包含参考文献）

literature review

the effects of different tasks are manifest in vocabulary acquisition. it means that the ability of vocabulary acquisition can be improved by a variety of tasks.

generally speaking, the main related tasks are below: reading comprehension and the listening input frequency.

in a series of studies (nagy et al. 1985; nagy et al. 1987; nagy and herman 1985, 1987), nagy and his colleagues defines theory which is widely accepted today in both first and second language acquisition. central to their theory is that incidental vocabulary learning is a gradual process in which gains are made in small increments with repeated encounters needed to gain full knowledge of a word.

2. 研究的基本内容、问题解决措施及方案

introduction

listening input frequency is closely related to an efl learners vocabulary acquisition. so far much research has been done on the effect of different tasks on efl learners vocabulary acquisition (nagy et al., 1987; dupy krashen, 1993; laufer, 2002; min, h-t, 2008; bao wang, 2013). but little has been done on the relationship between listening input frequency and efl learners vocabulary acquisition. this study is aimed to find out the definition of listening input frequency and its significance on english teaching. then make a conclusion with the former researchers empirical study.

during the past decades, much study has been conducted on different tasks of vocabulary acquisition of both l1 learners and efl learners (nagy et al., 1987; dupy krashen, 1993; laufer, 2002; min, h-t, 2008; bao wang, 2013).

for example, lots of literature confirms that reading is feasible and effective for vocabulary acquisition (nagy et al., 1987; dupy krashen, 1993), but less study about the relationship between listening and vocabulary acquisition. the experiment of dupy krashen, (1993) also proved the possibilities of acquiring vocabulary in audio and video mode.