17) It can't / may be a coincidence, but isn't it strange that I was thinking about John at the exact moment he called me?

В данном предложении нужно выбрать правильный модальный глагол, чтобы выразить сомнение в случайности. Подходящий вариант: may.

It may be a coincidence, but isn't it strange that I was thinking about John at the exact moment he called me?

Ответ: may