Since we have met again after all these years, let's____ each other from now on. A. keep up with B. keep out of C. keep in touch with D. keep touching 答案:CLichens
(地衣) are difficult to see. They
don’t move. They often mix into the living place. You might not even recognize
one if you are looking right at it.
Lichens
live on rocks, branches, houses, and even metal street signs. You can find
these colorful organisms (微生物) almost everywhere —
from deserts to rainforests, and from Antarctica to Africa. They’ve traveled in
outer space, and some scientists think there might even be lichens on Mars.
What you probably don’t realize
is that a lichen is more than a single thing. It includes two different types
of living organisms: a fungus (菌类) and an alga (藻类).
Neither of these organisms is a plant, so the lichen isn’t a plant either.
Through photosynthesis (光合作用),
the alga gets the sun’s energy to make food for the fungus, which is the place
for the alga to live in. However, the alga cannot leave the fungus.
Around
the world, scientists have found tens of thousands of types of lichens. Many
may not even have been discovered yet. As scientists continue to find new kinds
of lichens, they are also working to understand how they are connected to one
another. By putting together a lichen family tree, they hope to understand why
so many different types of lichens have grown in so many places around the
world.
Many researchers are trying to
understand basic facts about the organisms and their connections. Researchers
are also using lichens to examine the health of the environment.
1.What do we know about
lichens according to the passage?
A.
They will die if they leave Earth.
B.
There are more lichens than plants on Earth.
C.
They look similar to the environment around them.
D.
They are too small to be easily seen by people.
2.What does the second
paragraph mainly talk about?
A.
The way lichens live.
B.
The natural environment of lichens.
C.
The way lichens work as organisms.
D.
The family tree of lichens.
3.Which of the following
statements is NOT the scientists’ purposes of studying lichens?
A.
To understand basic facts about them.
B.
To creat a lichen family tree.
C.
To understand how lichens are related to each other.
D.
To understand why lichens can live in different places.
4.We can know from the
passage that __________.
A.
lichens can be used to better understand the environment
B.
lichens don’t have any differences in colors or sizes
C.
lichens don’t use photosynthesis like a green plant
D.
scientists have discovered every kind of lichen