填空题

Manmade fibers have only been used to make (36) for a little over a century, but their use is quite (37) nowadays. Rayon, the first manmade fiber commercially produced in the United States, appeared in 1910. In 1939, nylon, the first chemically (38) fiber, was first produced in this country on a commerical basis. Ever since, the number of manmade fibers has (39) into including more than 20 types. Although the (40) of manmade clothing fibers is long, rayon remains one of the most popular of all time, and that is why we continue to produce it in such great (41) . Rayon is made of cellulose, a naturally occurring (42) found in cotton and in certain vegetables, like celery, of all things. The cellulose in rayon has been recycled and treated to make it a useful fiber for clothing. (43) . Most rayon washes well, too, although it does shrink when it is washed in hot water. (44) . It wouldn’t be a good idea to leave a red rayon dress to dry by a sunny window. If you did that for very long, (45) . If you’ll just step this way. I’d like to (46) .