How could they be so sure that the sound of it would not bring someone on to them? It's a mere chance as it is that Mrs. Allen did not start out to inquire for the slamming door. Why did your guilty couple do all this, Watson?
他们怎么能肯定火枪的射击声不会把别人惊动，向他们奔来呢？象艾伦太太那样把枪声只当关门声而不出来查看，这不过是偶然现象罢了。华生，为什么你所谓的一对罪犯会这样蠢呢？