a matter of course的用法和样例：
- I check my in-tray every morning as a matter of course.
- Mothers as a matter of course have much affection for their children.
- I lock the door as a matter of course.
- Our vet is very efficient; he sends us a reminder when the cat is due for a booster vaccination as a matter of course.
- He took his duty as a matter of course.