I can't say...：我说不准……
当对某件事情不太有把握的时候，"I can't say"能表达你的这种不确定性，意思是“我说不准……”。
1. I can't say for certain.
2. I can't say who did the best.
3.I can't say with any certainty that eating less can be a cure for obesity.
A: Who do you think will win the championship?
B: I really can't say. Both teams this year seem really good.
A: There's a game on tonight. You want to watch it with me?
B: That sounds great!