Ink-jet printer belongs to nonimpact printers in which the characters are formed by projecting particles or droplets of ink on to paper. (71) printer is also a n0nimpact printer in which the characters are produced by applying hot elements to heat-sensitive paper directly or by melting ink from a (72) on to plain paper. Electrostatic printer creates an electrostatic latent image, which is then made visible by a toner and transferred and fixed on paper. An electrostatic printer may be used in some instances as a (73) . Laser printer creates, by means of a laser beam directed on a (74) surface, a latent image which is then made visible by a toner and transferred and fixed on paper. Magnetographic printer creates, by means of magnetic heads operating on a metallic drum, a latent image which is then made visible by a toner and transferred and fixed on paper. Computer-output-microfilm (COM) printer produces on a photographic film a (75) of each page.

（74）是（）

A.brightness

B.photosensitive

C.emitter

D.light-sensitive

不属于工业废水化学处理法的是（）。

A、化学沉淀

B、中和

C、汽提