The present study is to examine the effects of input flood,textual enhancement and the combination of the two on learners' acquisition of the syntactic rules of English manner adverbs and probe into their effects in depth.It is shown from the findings of this experiment that the three types of input enhancement are proven to be effective in helping the subjects acquire the rules.It is also indicated that the features of the subjects and the features of the target forms alike investigated play a part in the effects of these input enhancement techniques,showing it is conditional but not unconditional to apply these input enhancement techniques.It is also suggested that compound enhancement will not be statistically significant in comparison with single enhancement,when the single enhancement is effective enough in processing the target forms regardless of the generally better performance of compound enhancement over the single enhancement in processing target forms,showing it is not always necessary to use compound enhancement.