英语问题谢谢.1,This is my twin sister Luck. Both she and I-----goo

1,This is my twin sister Luck.Both she and I-----good at drawing.A am B is C are D be 答案C 不是指同一概念吗?
双胞胎姐妹俩也是两个人,所以是复数,用C are.
2,A fork and knife-----on the table.A are B is 答案B 这跟上面一样为什么是同一概念?
这是一副既可当fork有是knife的套件.从A fork and knife只有一个a可以看出来.
3,The doctor the writer-----from America.A is B are 答案B 这根第二一个意思为什么选B?
The doctor 和the writer 是两个人,所以是复数,用B are.
4,Bread and butter-----their daily food.A is B are答案A 为什么?
Bread and butter都是不可数的食物.用单数答案A is.