致心律失常型右室心肌病的病因可能为（）
A.病毒感染
B.冠心病
C.染色体显性遗传
D.糖尿病
E.结缔组织病
参考答案：C
Bob promises to join in the football match _____ he has to help his parents on the farm. [ ]
A. if
B. as
C. unless
D. when
编排思想
