题目内容：
One of the most common signs of Parkinson’s is tremor_____________．
A．if there isn’t enough dopamine m your body B．what affects muscles all through your body
C．which cannot be cured yet
D．if you have a fixed or blank expression
E．which may be the first symptom you notice
F．what causes Parkinson’s disease
参考答案：
答案解析：