同学你好，该知识点来自沪江网校《新概念英语2、3、4册连读【双11专享班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
sign签署
at once 立刻，马上
I will sign the contract at once.  我马上签合同。

on second这里后面还要加一个thoughts
on second thoughts 转念一想，又一想
'Wait there!' Kathryn rose. 'No, on second thought, follow me.'
“在那儿等着！”凯瑟琳站起身来，“不，我改主意了。跟我来。”

a day or two一两天
The pay was enough to keep him in whisky for a day or two.
这笔钱够他喝一两天威士忌了。

No, on second thoughts, I'd like to wait a day or two. 不，又一想，我想再等一两天。

祝同学学习进步~