Patterns using this form:
-nai [negative, plain]
→ Jump Start 2 - Lesson 11
-nakatta [past negative, plain]
→ Jump Start 2 - Lesson 13
-nai + to ikenai [need to/have to]
→ Jump Start 2 - Lesson 37
-nai + kutemo ii [don’t need to]
→ Jump Start 2 - Lesson 38
-nai + de [please don’t/without]
→ Jump Start 2 - Lesson 39