| 1 | So we need to get embryonic stem cells to form surface cells. | |
| 2 | They are very useful, for example, in understanding the properties of material surfaces. | |
| 3 | Mars is the only other planet that once had water on its surface - which is why scientists are looking for signs of life there. | |
| 4 | When these pholes "recombine" at the surface of the Earth, they enter an excited state. | |
| 5 | His team examined the effects of surface acting - or fake smiling - compared to what was termed 'deep acting', or cultivating positive emotions by recalling pleasant memories. |