| 1 | They walked two and two. | |
| 2 | Rabid mutualism doesn't just happen in pairs. | |
| 3 | Noah built an ark, which the animals came on to in pairs. | |
| 4 | They come at least in pairs, one serving as substratum for the other. | |
| 5 | As the couples closed upon him he expressed his congratulations . |