I'm concerned about his attitude.

I can't rest easy until he comes back.

I'm very anxious until he comes back.

I can't rest easy when he doesn't come home.

He told the story using the past tense.

Learning how to use past participles is important for understanding English.

He has acrophobia and is afraid to go up to the rooftop of a building.

He learned the past tense in Japanese.

Please check the archives of the BBS.

He took a deep breath to calm himself down.