1、The most common noun used in the world are friends, but the hardest thing to get is a friend.
世界上用得最普遍的名詞是朋友，但是最難得到的也是朋友?！▏?guó)。

2、The most common noun in the world is a friend, but the most difficult one is also a friend.
世界上最普通的名詞是朋友，但最難得的也是朋友。

3、With the most common noun is a friend in the world, but the most rare and friends.
世界上用的最普通的名詞是朋友，但是最難得的也是朋友。

4、This is an abstract noun, but it is used as a common noun here.
這是一個(gè)抽象名詞，在這里用做普通名詞。

5、The most common noun in the world is a friend, but the most difficult one is a friend.
世界上用的最普通的名詞是朋友，但是最難得的也是朋友。