not the [--形容詞--] thing to do

---な行動ではない・--な行為ではない

1.

The right thing to do is not always the easy thing to do.

2. I'm sorry I laughed at you. It wasn't a nice thing to do.

3. Keeping a dog and a cat together in a small apartment is not the wisest thing to do.

4. Taking a picture of a bear with a flash camera is not the smartest thing to do.

5. I realize it's not the fashionable thing to do, but I still drive a big car.