After this he immediately let himself in and began barking again. Suddenly, I thought a good idea: I can write it in my composition!

突然，我想到一个好主意：我可以把它写进我的作文！

youdao

I thought, "Wow, what a good idea."

我想: “哇，多妙的一个主意。”

《柯林斯英汉双解大词典》

I thought that would be a good idea as there'd be a lot of people around but I'm finding it a bit noisy.

我以为那是个好主意，因为周围会有很多人，但是我开始觉得有点吵。

youdao

And I thought it was probably a good idea to keep him there.

BBC: Complaint as Kent Police release 'caught intruder'

With NaNoWriMo well underway and writers around the globe hammering away at their keyboards like crazed woodpeckers trying to get at that tasty grub hidden just out of sight, I thought it might be a good idea to take a step back for a second.

FORBES: Five Links For NaNoWriMo Inspiration

And I expect someone thought it was a good idea - at the time - to introduce the rabbit and the cane toad to Australia!

BBC: Prince Charles speaks out against GM food