问题
选择题
It has been proved______eating vegetables in childhood helps to protect you against serious illnesses in later life.
A．if
B．because
C．when
D．that
答案
答案：D
此题考查that引导的主语从句的用法。句中的it是形式主语，真正的主语是eating vegetables in …life,所以要that引导这个主语从句，而that不作任何成分，也没有意义，故答案是D项。