unsure的反义词是什么

　　例句：

　　There were a lot of things I was unsure about.

　　有许多事情我没把握。

　　He was unsure of what to do next.

　　他对下一步该做什么犹豫不定。

　　Unsure of the meaning of this remark, Ryle chose to remain silent

　　由于不确定这句话究竟是什么意思，赖尔选择了保持沉默。