在梳理头发时，头皮屑大量脱落，好像下雨似的，这属于病理现象，在医学上称为（）

第三次科技革命具有范围广、影响大的特点，它给人类的生产生活带来巨大的变化。下列选项中属于第三次科技革命成果的是（ ）

A．蒸汽机和火车

B．内燃机和飞机

C．电报和电话

D．电子计算机和克隆技术

在探究“影响液体内部压强大小的因素“实验中：

（1）如图甲用手按压强计的橡皮膜，U型管内水面出现高度差；将橡皮膜放入酒精中，U型管内水面也出现高度差，这说明                     ；这种研究问题的方法是                           法；

（2）若在使用压强计前发现U型管中有高度差，通过________ 方法可以进行调节。

①从U型管内向外倒出适量水；

②拆除软管重新安装；

③向U型管内加适量水；

（3）比较乙、丙实验可知，液体内部压强与液体的_______有关 ；比较丙、丁实验可知，液体内部压强与液体的___________有关。

人工清淤是目前使用最普遍的方法，在渠道停水后，组织人力，使用铁锹等工具，挖除渠道淤沙，一般一年进行1～2次。

Passage Four

Read the passage below and then do the exercises that follow.

If a Mecca exists for today’s youth, it must take the form of a rock concert. Such a colossal event draws people from surprisingly distant places and from oddly diverging lifestyles. The sophisticated college student may be seated next to the wide-eyed junior high cheerleader, the latter showing fright at the approach of a wild-eyed freak. How do these incompatible character types find a mutual appeal in rock concert What induces young people to exchange the few dollars earned through babysitting or car washing for a concert ticket

To many, the answer is immediately obvious—the music is the source of appeal at a concert. The quality of the sound produced, however, frequently casts doubt on this explanation. Unquestionably, rock concertsare loud ; the decibel level of some reportedly exceeds that attained by a jet plane on takeoff. In addition, this aural assault is often intensified by an out-of-tune guitar, by the faltering voice of the performer, or by the bad acoustic in the concert hall. Rock groups generally correct these problems in a studio; their recordings may even boast pleasing harmonies with intelligible lyrics. So why do we battle crowds to secure choice seating at a concert creates a magical, otherworldly atmosphere, reminiscent of a childhood never-never land. An eerie darkness shrouds the hall, and then, just as in our favorite fairy tale, the supernatural being( otherwise identified by the vulgar term, "rock star") appears in a burst of light. In another context he would have been known as a" god out of the machine. " Bizarre lighting schemes and gimmicks such as mock hangings or fire-breathing contribute to the atmosphere of other-worldliness in some acts. The fans are permitted only a glimpse of the star before he vanishes once more in the darkness, only to materialize the following evening in a concert hall hundreds of miles away. The stage becomes the rock star’s only natural habitat; for us, he can have no existence apart from it. We can scarcely conceive of our idols performing such mundane activities as going to the dentist, shopping for tuna fish, or changing the baby, perhaps we have a need to believe in an illusory creature of the night, somehow different from ourselves. Who fits this description better than a rock star

What method/technique is employed to develop the above passage ？