1. I haven't been to the dentist for six months -> The last time 2. She has studied Japanese for 5 years -> She began

1. The last time I went to the dentist was six months ago.

-> the last time S V2/ed (lần cuối)

2. She began to study Japanese 5 years ago./She began studying Japanese 5 years ago.

-> began to V ~ began Ving: bắt đầu làm gì