Through sentence translation test by Chinese English learners, this article discusses segment elasticity in the acquisition process of sequence assembly, cognitive discreteness between RP and CT. The results showed that: four kinds of IC acquisition difficulty have much influence on partial distance of segment stretching, segment narrowing and slit reloading; there are hinge type sequence (weak tremor discretization), adhesive series (strong tremor discretization) and loose sequence (super tremor discretization) in three groups in RP and CT respectively. SET can help to reinstall the sequence of IC, reduce the difficulty of the acquisition of IC and optimize the structure of the sentence slot..