单项选择题
John had an argument with Henry,（）was known to all
A．what B．that C．this D．which
单项选择题 Is this house the one（）you once lived in your childhood
单项选择题 This terrible accident happened（）the cold evening of June 6, 1987.
单项选择题 I'm still unable to make myself（）in the discussion, which worries me a lot.
