| balloon |
a small bag made of thin material that is filled with air or some other gas and used as a decoration or toy. |
| busy |
doing something or working on something. |
| flight |
a trip on a plane from one place to another. |
| impossible |
not able to happen or to be done. |
| knock |
to hit a door in order to make noise. |
| muscle |
the soft pieces of flesh in animals and humans that make the bones move. |
| natural |
of or produced by nature. |
| often |
at frequent times. |
| pen |
a long, thin tool used for writing or drawing in ink. |
| program |
a plan of what will be done or take place. |
| slip |
to slide suddenly on a slippery surface. |
| smooth |
not rough; even. |
| square |
a flat, closed figure with four straight sides of equal length and four equal corners. |
| swap |
to exchange or trade. |
| vacuum |
a space or container in which there is no air or from which most of the air has been removed. |