The Hong Kong Polytechnic University online Centre for Independent Learning (CILL) has a section specifically for students studying English for Academic Purposes (EAP) It is designed to help learners improve their use of grammar in academic situations. There are 35 areas with accompanying exercises for students to choose according to the grammar problem the learner would like to work on most.

http://www2.elc.polyu.edu.hk/CILL/grammar.htm