A：why
B：when
C：which
D：where
“I don't think it's my ________ that the window suddenly broke. I just opened it, that's all,” said the boy in tears.
一只白公羊与一只黑母羊交配，生下的小羊全部表现为白色，此现象可解释为（ ）
— What do you think of tomorrow's football match? — _______ difficult for us _______ the match.
