与肺癌发病关系最密切的因素是
A．职业性致病因素B．长期吸烟C．免疫缺陷D．慢性肺部疾病E．遗传因素
参考答案：B
___ he will come or not is_____ worries us.
A．Whether, why
B．Whether, what
C．If, that
D．If, which
肾小管的分泌
