see something with half an eye
不费力气看出
A:You're in love with Mary, right?
A:你爱上了玛丽，对吗?
B:You're pulling my legs!
B:别开玩笑了!
A:I'm not blind. Anyone can see that with half an eye.
A:我眼睛可不瞎，谁都能毫不费力地看出来。