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Many animals use some kind of “ language” . They use signals that have meanings .For ex - ample , when a bee has found some food，it goes b_1__ to its home . It is easy for a bee to t__2__ the other bees where the food is by speaking to them , but it can do a little dancing . This tells the bees where the food is and how f__3__it is .

Some animals show how they feel by m__4___  sounds . It is not d__5___  to tell if a dog is angry because it barks（吠）. Birds make several different sounds and e_6___  has its own meaning . Sometimes we humans make sounds in the same w __7__. We make sounds like “Oh!” or “Ouch !” to show how we feel about something or when we d__8__ something on our feet.

We humans also have languages. We have words. These words have the m__8___ of things, actions , feelings or ideas . We are able to give each other messages to tell w__10__ we think or how we feel . By writing down words , we can remember what has happened or s__11___ messages to people far away.

Languages can live and die . If a language isn’t u__12__by people , it is called a d__13__ language. This language cannot  live and grow because no one s_14__it. Latin is an example of a dead l__15__.

A living language , of course , is often s_16__ by people today . It grows and c_17__ with time .

New words are created（创造）, and some old words have n 18  meanings . Some words , or their meanings, may die and only be found in the old b_19__. English and Chinese are b__20__ examples of a living language.

It is easy for us to tell who our family members are, but do plants recognize(识别) their own family? Some do, scientists say, according to a report by Science News in early 2010.
Guillermo P. Murphy and Susan Dudley are two plant scientists from McMaster University in Hamilton, Canada. They did a few experiments with Jewelweeds, a kind of flower that grows in wet, shady spots. They found that the flowers seem to know their own flower family. In their experiments, Murphy and Dudley planted jewelweeds in pots with either siblings or strangers.
When jewelweeds were planted in pots with strangers, the plants started to grow more leaves than if they had been planted alone. This response(反应)suggests that plants are competing with strangers for sunlight, since a plant with more leaves can receive more light and make more food. Jewelweeds usually grow in the shade, where sunlight is not enough.
When jewelweed seedlings(幼苗)were planted with siblings, they grew a few more branches than they usually would if they were alone – but they did not start growing lots of extra leaves. This behavior suggests the plants are more likely to share resources, rather than compete.
According to the Science News report, Jewelweeds are not the first plants that plant scientists have studied for family recognition. In 2007, Dudley and her team studied the Great Lakes sea rocket, a plant that grows on the beach – where it may be hard to get fresh water. In that experiment, the scientists found that when sea rockets were planted with siblings, they tolerated each other. But when they were planted with strangers, the sea rockets reacted by working extra hard to grow lots of roots.
Dudley says this just because sea rockets, on the beach, get plenty of sun but struggle for water – so when they’re threatened, they compete for water. Jewelweeds have plenty of water but have to compete for sunshine, so they grow more leaves.
【小题1】 What does the underlined word siblings mean?