1.What do you have to lose? 你能有什么损失呢？（为什么不尝试一下呢？）
lose v. 损失，丧失，失去

2.It's worth a shot. 值得一试。
shot n. 尝试，努力
shot at sth/at doing sth
I'm willing to give it a shot.
我愿意试试。
I've never done this before but I'll have a shot at it.
我们从没做过这个事，但是我愿意尝试一下。

3.You might as well. 你试试也无妨。
may/might (just) as well do sth 做.....倒也无妨；倒不如
We might as well walk there.
我们倒不如走过去算了。
We may as well start the meeting -- the others will be here soon.
我们不如先开会吧，其他人马上就到了。