从她的表情，我能看出她很不高兴。

I ___can ___tell that she is upset from her expression.

对他这个人，你永远搞不清他是不是在开玩笑。

With him, you ___can never ___tell if he's joking.

即使是在电话里，我也能听出母亲什么时候在担心。

Even over the phone, I ___can ___tell when my mother is worried.