toss-up
US /ˈtɑːs ʌp/
UK /ˈtɑːs ʌp/

名词
1.
未知数, 势均力敌, 不确定性
a situation in which either of two choices or results is equally possible and it is impossible to predict which will happen
示例:
•
It's a toss-up whether she'll get the job or not.
她能否得到这份工作还是个未知数。
•
The election is a real toss-up between the two main candidates.
这次选举是两位主要候选人之间的真正势均力敌。
在 Lingoland 学习这个单词