[简答题]{{B}}Section D{{/B}}
Directions: You are going
to read a passage. Seven sentences have been removed from it. Choose from the
sentences A-H the one which fits each gap. There is one extra sentence which you
do not need to use.
Bacteria are extremely small living things. While we measure our own sizes
in inches or centimeters, {{U}} (72) {{/U}} . One micron is a thousandth
of a millimeter; a pinhead is about a millimeter across. Red-shaped bacteria are
usually from two to four microns long, while rounded ones are generally one
microns in diameter. Thus, if you enlarged a rounded bacterium a thousand times,
{{U}} (73) {{/U}} . An adult human magnified by the same amount would be
over a mile (1.6 kilometers) tall.
Even with an ordinary
microscope, you must look closely to see bacteria. {{U}} (74) {{/U}} ,
one finds that bacteria are barely visible as tiny rods or dots. One cannot make
out any things of their structu