Un sitio bastante completo donde puedes encontrar una extensa variedad de ejercicios interactivos autocorregibles y su versión también en pdf que el autor permite descargar, esto es lo que escribe el autor de este sitio:

«Grammarism is a website you can practice English grammar online and download printable pdf worksheets. It’s free. There are hundereds of interactive quizzes and printable worksheets for all English topics such as present simple or relative clauses. Every test is a little bit harder than its previous one. All the exercises were automatically generated by algorithms based on sentences in public domain books. The exercises and worksheets can be used for self-study, for commercial purposes such as writing books or classroom activities. There is (almost) one person are two persons behind the project. It was conceived around August 2019 and took almost 2.5 years to make it alive. (released on January 17th, 2022) Project was initially called Zentence (zen + sentence = zentence). Zen for simplicity. Project was then called Sentense (sentence + tense = sentense).  If .com domain wasn’t taken, you would be reading this text on However, Grammarism name represents better the philosophy of the project. Data-driven approach for English learning and teaching. Mathematics, statistics, linguistics, programming, machine learning way. Lots of new features are already planned.  It’s very pleasing and exciting that the project reached you. Hope that it is useful. Feel free to reach out for any reason. Let’s talk and decide together where it goes. Let’s make English learning/teaching simpler, easier, less time-consuming and more automated.  Grammarism was previously being created in bestmenland, a tiny town where people used to be kind and happy.  Grammarism is currenty being created in a tiny university, where people has always been kind and happy.»