Does Age Affect Strength of Wood? A test of the floor joists (托梁) of the Octagon House, Washington, D. C. , shows joists that were cut form virgin Southern yellow pine of high quality to be as strong as when they were installed more than 150 years ago.
Mechanical test by the Forest Products Laboratory showed that the timbers were strong enough for their purpose and differed little from the strength of similar newly-cut timbers. The tests were made on sections from several parts of the joists. No decay was found.
1. The passage gives a general description of contributions made by forestry.
2. Forest fires caused by lightning occur more frequently than those caused by man.
3. Blister rust is a serious destroyer of white pine trees.
4. The strength of wood-frame houses depends on what sort of nail is used.
5. The time when yellow pine was cut to make floor joists prevented them from decaying.
6. The bird and rodent repellent, made up of tetramethyl thiuram disulfide does not affect germination of the seed.
7. The Forest Service scientists are likely to help fulfill America's timber demand by saving the American chestnut.
8. Each time a forestry problem is solved by research, forestry_______.
9. _______pines is a way to get more seed from better trees.
10. The honeycombed honeycombed(蜂窩結(jié)構(gòu)的) paper becomes resistant to moisture and decay when it is treated with_______.
I. Y 2. NG 3. Y 4. N 5. N 6. Y 7. Y
8. advances one more vital step 9. Girdling/Chipping 10. synthetic resins
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