Day after day, he continued to strive to solve the problem.

I have been to Thuringia.

I use plain flour to make bread.

He proposed a new theory about quantum mechanics.

Thanks to his serendipity, we were able to find a new business opportunity.

Intermolecular forces are an important factor in determining the properties of a substance.

Katoriki is a rare name, isn't it?

She gave him a kiss.

He kissed her.

The mouse squeaked 'chu'.