Betty is an American girl. She is thirteen. She is in Beijing with her parents. She doesn't know much Chinese. She can't speak Chinese well. Sometimes her friends don't understand her.

    It's Sunday morning. She is going to the zoo to see pandas. She is waiting at a bus stop. At the bus stop she asks a boy which bus to take to go to the zoo. But the boy can't understand her. Then she takes out a pen and a piece of paper. She draws a panda on it and shows the picture to the boy. The boy smiles and then shows her the way to the zoo.

下列几种做法中，符合安全用电的是(     )