题目

阅读短文，根据短文内容回答问题。Confidence is very important in daily life. It can help you to develop a healthy attitude. A study shows that the people who are more confident are much happier. They can have more chance to make themselves successful. But how to be more confident? Here are some suggestions:   Speak loud   When you are not confident, you can’t do well what you want to do. You speak in a voice so low that other people can hardly hear you. Try to speak loud enough so that people can hear you clearly. The high voice can help you become more confident.   Pla如图装置分别通电一段时间后，溶液的质量增加的是（　　） A、B、C、D、