1.1. Where did the twins have their second birthday?

A In the mountains.

B On a farm.

C At school.

D At Ocean Park.

解析：选D。D细节理解题。根据原文“they had their second birthday at Ocean Park”可知双胞胎在海洋公园过两岁生日。故选D。

2.2. What was in the birthday cake?

A Carrots and bamboo.

B Rice and fish.

C Eggs and milk.

D Grass and leaves.

解析：选A。A细节理解题。根据原文“It had frozen carrots and fresh bamboo”可知蛋糕里有胡萝卜和竹子。故选A。

3.3. How old are the twins now?

A One year old.

B Two years old.

C Three years old.

D Five years old.

解析：选B。B推理判断题。根据原文“they had their second birthday”可知双胞胎刚过第二个生日，即现在两岁。故选B。

4.4. What will happen to the twins soon?

A They will have another birthday.

B They will eat more carrots.

C They will live alone.

D They will stay with their mother.

解析：选C。C推理判断题。根据原文“Soon they will live by themselves”可知双胞胎很快将独立生活，不再和妈妈同住。故选C。