"This book belongs to the collection ""Practica tu espanol"" that shows the most difficult aspects of Spanish as a second language. These self-study workbooks deal with some of the most difficult aspects of Spanish. Grammatical and lexical contents are explained (in Spanish) accompanied by abundant examples. An answer key is included. The series consists of: Los tiempos de passado (level B1); El lexico de los negocios (level B2); Practica la conjugacion (level A10); El subjuntivo (level B1); Las preposiciones (level B1); Las expresiones coloquiales (level B1); Ejercicios de pronunciacion (level B1 - comes with its own CD); Ser y estar (level B1); and, Marcadores del discurso (level C1) and Ortografia (levels A2-B1)."