单项选择题
A．When you are in a state of subhealth, you shoud go to see a doctor and buy some medicine.
B．When you are in a state of subhealth, you should stay home and keep silent.
C．When you are in a state of subhealth, you should find out the reasons and relax yourself
D．When you are in a state of subhealth, you shoud have yourself examined in foreign countries.