Abstract:
This study is an investigate the impact of grammatical errors on EFL learners writing. The areas which the study investigated were, subject verb agreement, the prepositions and, past simple versus present perfect. The study population was composed of the 4th year students studying English language at the college of languages, Sudan University of science and Technology. The data collection tool was a test given to the students to write a composition, the data collected was analyzed by the researcher's own observation and a computer program. The important findings are : the researcher found that, most of the students are unable to understand and deal with the prepositions in writing, most students failed to use subject verb agreement. which is a big problem to students to express themselves The study recommended that: teachers should give enough time and effort to teach writing skill, and help the students to improve their writing performance by providing them by the rules of a language "grammar". Students should practice their writing skill by doing more writing activities. At last, it hoped that the results of this study could be much of benefit for developing English writing skill among university's' students, particularly Sudan University of Sciences and Technology.
