Everything on our earth     1     （be）made of matter, in     2     form of solids such as wood or iron, liquids such as water or milk and gases such as steam or air. Solids, liquids and gases are called the three     3     （state）of matter. If you put a piece of ice in a pan and heat it     4     （gentle）, it soon melts and becomes a liquid we call water. If you then heat the water until it boils, it forms a gas     5     （call）steam.

Solids are of different shapes and sizes and very stable. It takes lots of energy     6     （transform）the shape of a solid. The size of a solid will not change unless it is heated or cooled. Liquids do not have a shape, but simply take the shape of the container they are poured     7     . Like liquids, gases do not have a     8     （fix）shape and have good fluidity（流动性）,     9     expand to fill all the space inside the container. Therefore, a gas leak in the kitchen of your house can     10     （smell）quickly in another room of the house.

Recognizing a cat’s emotions from its face is often hard, even for its owners. Now, researchers from Canada’s University of Guelph insist that cats also express emotions on their faces—one just has to learn     1     to interpret them!

For their study, Professors Lee Niel and Georgia Mason surveyed 6,300     2    (volunteer) from 85 countries. The participants     3    (show) the cats’ faces from a series of short videos.

The researchers, who published their findings in the November 2019 issue of Animal Welfare, found that only 13 percent, or 819 participants, were able to read the cats’ emotions     4    (accurate) over 75 percent of the time. Further research showed that the so-called “cat whisperers” were primarily women and veterinarians(兽医), Younger adults also seemed to be able to read the expressions even     5    (well) than older individuals.

Surprisingly, being a cat owner did not help study participants,     6    (indicate) that a strong attachment     7     the animal did not necessarily mean better understanding of its emotions.

The researchers believe cats’ expressions can be learned over time,     8     explains why veterinary staff scored high in the study. “This is important to be able to do because it could help strengthen the bond between owners and cats, and so improve cat care and welfare.” said Niel.

    9    (find) out if you have what it takes to be a “cat whisperer,” take the fun cat faces quiz     10    (create) by the study’s researchers.