1.Experts point out that the emphasizing in
oratory is on the skillful utilization of the voice.
2.As far back as 1940s there were already
recording machines that encoded sounds,
pictures, and other informations onto
magnetic tape.
3.Highly precise measurement have been shown
that variation in the Earth’s rotation is
largely controlled by climatic conditions.
4.Her musical career ,unlike most people
who played a musical instrument ,did not end when she left college.
5.High-grade written paper is frequently
obtained from cotton rags.
6.19.Always since the creation of celluloid ,
plastics have been found to have a multitude
of industrial and commercial uses.
7.It is estimated that a scientific principle has a life expectancy of approximately a
decade before it drastically revised or
replaced by newer information .

试一下:
1、the emphasizing on
oratory is in the skillful utilization (on与in换一下）
2、
3、Highly precise measurement have （has)
4、unlike most people ('s one)(指career）,who played a musical instrument
5、obtained from（made from)
6、Always since （Since)
7、 it drastically ( it was drastically )