What does this sentence mean?

He picked up a pen to write down the poem.

It's difficult to remember the stroke order of kanji.

He is studying about the metamorphosis of insects.

The three states of matter are solid, liquid, and gas.

It's difficult to understand his mental state.

Kōkotsubun is an ancient Chinese script, one of the oldest scripts.

He is good at reading Chinese text.

Fumiko is my best friend.

He wrote a written prayer for the New Year.