There are a lot of supporting materials in this textbook, and there are special workbooks corresponding to the textbook. Many of the above special exercises are very helpful for practicing grammar, although they are all mechanical exercises. I also use the teacher's book, which contains the answers to textbooks and workbooks. If I can do it seriously, I believe I will practice the basic grammar well. You can learn about grammar through the contents of the textbook, because you have a foundation. The yellow book "Interpretation and Practice of Standard German Grammar" published by FLTRP is quite good. If you are a German major, you can buy one. You speak grammar very well.