根据图示，用适当的词语来表明下面各家庭成员之间的关系。

1. John and Helen are Jack's g        .

2. John is Jack's g        .

3. Helen is Colin's g         .

4. David is Jack's f       .

5. Sally is Jack's m      .

6. Jack is Colin's c       .

7. Mary is John and Helen's d       .

8. Peter is David's b        .

9. Mary is Peter's s         .

10. David and Sally are Jack's p       .

甲酸分子中既含羧基，又含醛基，因此它既具有羧酸的性质，又具有醛的性质。在饱和一元酸中，甲酸的pH值最小。