2 pair out on a Friday night, coupled. Yeah, a double date.

两对情侣在周出去玩玩，成双成对的。是的，四人约会。

When your wife dies, it must be depressing to see other people in a loving relationship.

谁的妻子死了 看见成双成对的幸 心里都会舒服的。

Pigeons live in pairs, and the mates are very fond of each other.

鸽子是成双成对地生活的, 彼此非常恩爱。

Not always, and not in pairs.

都是 更会成双成对的。

Only about 3% of mammals are monogamous, and, although 95% of birds pair off (at least for one breeding season) , paternity tests have revealed that the avian world is chock-full of cheaters.

只有大约 3% 的哺乳动物是一夫一妻制，虽然 95% 的鸟类都是成双成对的（至少在一个繁殖季节内），但亲子鉴定显示，鸟类世界充满了骗子。