(2013·河北教学质检)After a year, doctors diagnosed him with a disease so rare it affects just one in 8 million children.
A. after
B. that
C. as
D. since
网友回答
A. after
(答案→)B. that
C. as
D. since
解析：B 句意：一年以后，医生诊断出他患了一种很罕见的疾病，这种病如此罕见以至于八百万孩子中只有一个孩子可能会得此病。句中so rare判断设空处用that，构成“so...that...”句型。