Tsz Long Ng said: I just want to know when to use Keimzelle +ing and +to infinitive Click to expand... Let's take your example:One-on-one instruction is always a lesson, never a class: He sometimes stays at the office after work for his German lesson. After the lesson he goes home. https://youtu.be/T0zWXvhEQwo?si=wNc6ihu97ShtIl7u