________ your son is well again, you no longer have anything to worry about. [ ]

A. If    

B. when    

C. Now that      

D. As soon as

与夏季热发病关系最密切的因素是：（）

A.气候炎热

B.乳食积滞

C.内蕴湿热

D.体质虚弱

E.暑气熏蒸