He workes very hard，so he doesn't take many break，just finished his lunch，suddenly he heard someone knocked his door，so he grabs his keys and opens the door

Susan and Mike are planning to go on an official date and have a dinner at the very Top level restaurant. However, Susan is too much eager to go out with Mike, and she rushed to the Mike house and find Mark is still in the house.  So she just knock at the door. And when Mike hears the knock, he just grabs his keys and opens the door in a very short time