【正文】 rectness when he uses the learned knowledge Even when we have time, we may be so involved in what we are saying that we do not attend to how we are saying it. 3) Rule knowledge: In order to use the rules, the learner has to know them .That is to say, one has to have an appropriate learned system in order to apply it. Input HypothesisThe Input Hypothesis is central to Krashen’s SLA theories. First, attempts to explain how we do acquire language. Krashen gives us “Humans acquire language in only one way—by understanding messages or by receiving “prehensible input”.That is to say, language acquisition depends on trying to prehend what other people are saying .The learner should focus on meaning ,but not on form .If a learner hears a meaningful speech and makes efforts to understand it ,acquisition will occur . If a learner concentrates on the forms of language ,then acquisition will fail .Second, it also attempts to explain how a learner progresses in acquisition Krashen provides us with a model like this: “We progress along the natural order by understanding input that contains structures at our next stage—structures that are a bit beyond our current level of petence.” Suppose the current level is “i” ,the next stage should be“i+1”(stage able beyond the current level).Learners can understand language containing un acquired grammar with the help of context, including extralinguistic information, knowledge of the world ,and previously acquired linguistic petence . Hypothesis“Affective filter” is a mental block that prevents acquirers from fully utilizing the prehensible input they receive for language acquisition. That is to say, in order to acplish the task of acquisition ,prehensible input is only a necessary condition ,but it alone is not sufficient ,the acquirer needs to be “open” to the input .People should not put the acquirer “on the defensive” ,because when the affective filter is up, the acquirer may understand what he hears or reads, but the input will not reach the language acquisition device. This occurs when the acquirer is unmotivated, lacks selfconfidence or feels anxious .The effective way to lower the affective filter is either to make him care nothing about the failure in language acquisition or to consider himself to be a potential member of the group using the target language. The above are the five famous hypotheses in the field of SLA. Krashen stated: We can summarize the five hypotheses with a single claim :people acquire a second language only if they obtain prehensible input and if their affective filters are low enough to allow the input ‘in’ .When the filter is “down” and appropriate prehensible input is presented ,acquisition is inevitable.2. Current Situation and Main Problems of English Reading Teaching in Senior High School Students’ Current Situation and Main Problems Unfamiliar to Vocabulary and GrammarVocabulary is the key to the reading. The main problem of reading is the vocabulary and its significance. The small vocabulary cannot expand the reading quantity, narrow to lexical meaning39。s second language acquisition theory to guide and explore the process of foreign language teaching, which has the important meaning to improve the high school English reading teaching methods, improve English reading teaching quality. The purpose of the research is based on present situation of high school English reading teaching, analysis of the existing problems in teaching. Application Kkrashen’s second language acquisition theory on high school English reading teaching, and then solves some problems in teaching, optimize the teaching mode. Our country English teaching may profit from the reasonable factor of Krashen39。s process, their hope depends on “hits attacks, holds the Buddha foot at the last minute” to improve English scores, have never realized English study is a longterm accumulation process. These problems are worth our attention and thoughtful. Teachers’ Current Situation and Main Problems Teaching Concept and Single Teaching ModeAccording to the survey，many teachers influenced by the narrow examoriented education, who still follow the traditional translation teaching method for teaching .This approach had long occupied in English class, which emphasized on the teacher39。 reading and prehensive ability in using English. of StudentcenterEnglish Curriculum Standard pointed out that the teacher must guide the student to develop the independent learning capability consciously, make students bee study center. That is to say, teachers should change their role in teaching. Teacher is not only the impart person , but also should bee the promoter, director and helper to students. The investigation discovered that the partial students have the greatly strengthened dependence to teacher. Teachers manage tightly, then the result progresses quickly, otherwise bogs down, even regresses. That showed the student have played the wrong role in the class. This problem in English teaching is also not allow to neglect. The student39。 prehensive application of investigation of language ability. It is an effective method to increase students’ vocabulary, consolidate their English knowledge, enlarge their scope of knowledge, improve their reading speed, and cultivate their reading ability. Extensive reading content is narrative, and the aspect of knowledge is mostly broad. It’s not only benefit for students’ eyeopening, validation, consolidate, enrich the text content, naturally absorb the language, but also it is benefits for students to increase language sense , to improve the English language and cultural level may also help cultivate observation and judgment.And from the perspective of language input, extensive reading belongs to the prehensible input, the prehensible spoken language input occurs through the students’ unconsciousness in hidden study. This course makes students acquire language ability. Students are faced with lots of inpu to