I have no idea ＿＿＿ David is in trouble he will turn to you for help.A. ifB. thatC. whenD.

问题补充：

I have no idea ＿＿＿ David is in trouble, he will turn to you for help.

A. if

B. that

C. when

D. that if

答案：

A. if

B. that

C. when

(答案→)D. that if

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