[单项选择]Bacteria are microscopic organisms which live on the surface of objects. They are one of the most ancient living things, which exist on this planet for nearly 4,000 million years. Do you know the size of bacteria It can only be measured in microns. Maybe you have not a standard in your mind how long a micron is. One micron is a thousandth of a millimeter, which equals about the diameter of a pinhead. Therefore, even if we enlarged the rounded bacterium a thousand times, it would only be the size of a pinhead. We barely see bacteria by a magnification an ordinary microscope of 100 times, even if we try, we cannot make out anything of their structure. There are normally millions of them together, for they can multiply really fast.
Scientists have found that some bacteria have attached to wavy-looking "hairs" called flagella. The flagella rotate, pushing the bacteria through the water. Others can glide along over surfaces by some little-understood mechanism. Bacteria are so small
A. Flagella are part of bacteria.
B. Flagella help bacteria to move.
C. Flagella are always going round and round.
D. Flagella are like waves.

[单项选择]Bacteria are microscopic organisms which live on the surface of objects. They are one of the most ancient living things, which exist on this planet for nearly 4,000 million years. Do you know the size of bacteria It can only be measured in microns. Maybe you have not a standard in your mind how long a micron is. One micron is a thousandth of a millimeter, which equals about the diameter of a pinhead. Therefore, even if we enlarged the rounded bacterium a thousand times, it would only be the size of a pinhead. We barely see bacteria by a magnification an ordinary microscope of 100 times, even if we try, we cannot make out anything of their structure. There are normally millions of them together, for they can multiply really fast.
Scientists have found that some bacteria have attached to wavy-looking "hairs" called flagella. The flagella rotate, pushing the bacteria through the water. Others can glide along over surfaces by some little-understood mechanism. Bacteria are so small
A. Bacteria are as big as a pinhead.
B. Bacteria can not be seen by an ordinary microscope.
C. Bacteria are hard to see because they often live together.
D. Bacteria are very small so they can only be measured in microns.

[单项选择]Which is the branch of linguistics which studies the characteristics of speech sounds and provides methods for their description, classification and transcription
A. Phonetics.
B. Phonology.
C. Semantics.
D. Pragmatics.

[填空题]Experiments in which animals live in artificial surroundings show that

[单项选择]Which floor does Mary live on
A. The fourteenth floor.
B. The sixteenth floor.
C. The fifteenth (第十五) floor.

[单项选择]Which floor does Linda live on
A. The fourth floor.
B. The sixth floor.
C. The fifth floor.