英文中,Grangpa Grandma中的G要大写,mum dad的第一个字母是否要大写?我在许多书上看到都是小写的，但我以前学得好像是要大写的，如果有人知道，请帮帮我。

要.

Capitalize words such as Mother, Father, Grandmother, Grandfather, Son, Daughter, and Sis (sister) when they are used in place of the person\'s name. Do not capitalize them when they follow possessive pronouns such as my, your, his, her, our, or your.
Examples: I will ask Father. I will ask my father.
Capitalize each word that needs a capital letter.
Exercise:
1. my father will return next week.
2. Oh, mom, you don\'t understand me.
3. Tomorrow grandmother leaves for Florida.
4. Did sis want to go with us?
5. Today mother and i will finish the painting.

Answers
1. My
2. Mom
3. Grandmother
4. Sis
5. Mother/I
http://www.dailygrammar.com/301to305.shtml

不一定必须大写.英文的习惯也是会改变的.Grangpa Grandma也不一定大写.这些并不妨碍理解,不要去深究.学得太死板不好.