根据汉语提示完成下列句子。

①-Will John help us?    

-___________ （当然）!  He is kind and warm-hearted.    

②I have_____________ （下了赌注）that our team will win the first.    

③He has just___________ （打赌输了）．    

④It was crazy of him to__________ （以……打赌）one of his fingers.