で (manner/state)

Yoshiki is grumbling 'it's cold, I don't want to' through a crying face.

I went to Sendai and came straight back without stopping.

On TV, someone with a grave expression is talking about the problems facing our country's future.

They poured water into the glass with a smooth, elegant motion.

Don't do that halfheartedly.

I got a free ticket.

She spoke to me in a low voice.

She spoke to the children in a gentle voice.

She writes with her left hand.

She spent the weekend alone.

She did the job by herself.

The train runs nonstop to Nagoya.

The train ran at a speed of 500 miles per hour.

Yumi went there by herself.

My friend got a good score on the English exam.

Please explain that in simple terms.