instinct
本能，直觉  

例句：
Birds learn to fly by instinct.
鸟儿学飞是出自本能。

stay focused 
集中思想于目标上

例句：
The only way to attain your goals is to stay focused and work hard.
达到目标的唯一办法就是集中思想于目标上并努力工作。
 

It's a toss-up.
这是没准儿的事。

对话：
A: Will Jack come back home for dinner?
B: It's a toss-up. He said he might work overtime today.
A: Then, let's start dinner without him.
　
A：Jack回来吃晚饭吗？
B：这是没准儿的事。他说他今天有可能加班。
A：那么我们就先吃不等他了吧。