根据句意及首字母提示补全单词。

1. W_____ is your mother's birthday.

2. Christmas(圣诞节) is in D_____.

3. September t_____ is Teachers' Day.

4. My b_____ is October 21st.

5. Dave had a birthday p_____ yesterday.

铁磁性材料近表面缺陷形成的漏磁场强度的大小，和缺陷埋藏深度成正比。