他的父亲作为担保人，确保他会按时偿还贷款。

His father acted as the ___surety to ensure he would repay the loan on time.

房东要求我们支付两个月的租金作为押金。

The landlord asked us to pay two months' rent as a ___surety.

他回答问题时充满自信，没有丝毫犹豫。

He answered the question with complete ___surety, without any hesitation.