That plan is too impractical, it's difficult to implement.

I'm troubled by his unproductive attitude.

He was affected by secondary effects.

Thinking sensibly, that plan will not succeed.

This is a preliminary plan.

He is interested in diachronic linguistics studies.

He is interested in synchronic linguistics.

That theory is unscientific and has no evidence at all.

He accidentally held her hand.

He is thought to be a very unsociable person.