Thank you for giving me this chance to ask for help.I am studying for master degree & want to make a research on the problems facing Sudanese students in learning English .Can you ,please help me in doing my research?i.e. to write the areas of difficulties for foreign learners ,e.g. students find it difficult to distinguish between the use of the present simple & the present perfect tenses,etc. & how can teachers solve such problems?
Thanyou for being patient & i am so grateful to you.
I am afraid that this is too broad an area to answer directly, Guest, as the difficulties in learning any L2 (of which English is only an example) are very much dependent on the nature of L1. The problems facing Sudanese students of English may be quite different than those facing Chinese or Spanish students of English.

As you begin actively working on your thesis, we will be happy to try to answer any specific questions that arise for you.
Being a specialist in applied linguistics, I should tell you that Arab students learning English as a SL/FL face the same problems due to several factors. Some of them are related to the nature of L2. Some others related to the interference. Usually, non-native speakers try to transfer some habits from L1 into L2. Specifically speaking, students find it difficult to master, for example, tense which are not available in L1 like the present perfect tense. It is also because of the non-systematic or irregularities of the pluralization. Examples: boy-boys, man-men, child-children, foot-feet, mouse-mice, ox-oxen, analysis-analyse.s, etc. Good Luck you need it