It’s very difficult ………….. this lesson.

It's very difficult on this lesson.

The answer is-
On

Artinya:
sangat sulit dalam pelajaran ini….

__________________________
Sorry if it's wrong….
(・・)

1. It's very difficult in this lesson < jawabannya: in

Atau

This lesson it's very difficult. < Di susun doang Dan tidak Ada jawabannya

Sorry if it's wrong
Maaf jika salah _(._.)_