Questions with the keyword 'sad'

• How can you tell if an animal is happy or sad? Is it whether they make a noise or move or? by Katch to Carrie, Ellen, Rupert Comments: (No comments so far )
• What was the saddest thing you have experienced as a scientist? by ErinM2017 to Carrie, Cedric, Ellen, Ines, Rupert Comments: (No comments so far )