【正确答案】正确答案：Similarities between first and second language acquisition: (1)Both L1 and L2 are constructed from prior conceptual knowledge. Language emerges as a procedural acquisition to deal with events that the child already understands conceptually and to achieve communicative objectives that the child can realize by the other means. (2)Second language learners seem to use similar strategies to those learning their first language. (3)Overgeneralization and transfer are used by both L1 and L2 learner as the result of a necessity to reduce language to the simplest possible system, as an effort to lessen the cognitive burden involved in trying to master something as complex as language. (4)The L2 learner, like the first, attempts to " regularize, analogize, and simplify" in an effort to communicate. (5)Speech addressed to children(motherese)and speech addressed to foreigners(foreign talk)present similarities; shorter sentences, high-frequency vocabulary, "here and now" times, indirect correction, frequent gesture, lake of overt attention to form. (6)A reasonable hypothesis is that the brain and nervous system are biologically programmed to acquire language(L1 and L2)in a particular sequence and in a particular mode(silent period). (7)Both groups are probably using the same learning process. For example, the L2 sequence for English grammatical morphemes was similar, though not identical, to that found in L1 acquisition. Other similar sequences of syntactic acquisition have been found in L1 and L2 learning. L2 learners , like L1 children, at first put negative elements at the beginning of the sentence " No the sun shining" and then progress to negation within the sentence " That"s no ready. " Differences between L1 and L2 acquisition; (1)L2 learners are usually older when learning their L2. Therefore, they are more developed cognitively. They have a greater knowledge of the world in general; they have more control over the input they receive; they are able to learn and apply rules that may aid in facilitating the acquisition process; they have one or more cultures that give them advanced information about expectations, discourse in general, and how to get things done with language. (2)Older learners may have increased inhibition and anxiety and may find themselves afraid to make errors(poor attitudes and lack of motivation); there might be interference from the L1, particularly from items that are similar, either structurally or semantically. (3)L1 acquisition is completely successful, but L2 learning is not. The evidence for this deficiency is held to be the lack of completeness of L2 grammars or the fossilization in L2 learning where the learner cannot progress beyond some particular stage, both familiar " facts" in some sense. (4)The variation in situation and other factors also produces many differences between L1 acquisition and L2 learning. L1 children mostly acquire language in different settings with different exposure to language than L2 learners and they are at different stages of mental and social maturity. In all, the differences exist in levels of cognitive development and affect and the similarities exist in the process of acquisition itself.