阅读下面这篇短文，短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为规定段每段选择1个正确的小标题；(2)第27～30题要求从所给的6个选项中选择4个正确选项，分别完成每个句子。
1. Thousands of years ago man used handy rocks for his surgical operations.
Later he used sharp bone or horn, metal knives and, more recently, rubber and
plastic. And that was where we stuck, in surgical instrument terms, for many
years. In the 1960s a new tool was developed, one which was, first of all, to be
of great practical use to the armed forces and industry, but which was also, in
time, to revolutionize the art and science of surgery. 2. The
tool is the laser and it is being used by more and more surgeons all over the
world, for a very large number of different complaints. The word laser means:
Light Amplification by Stimulated Emission of Radiation. As we all know, light
is hot; any source of light--from the sun it self clown to a humble match
burning--will give warmth. But light is usually spread out over a wide area. The
light in a laser beam, however, is concentrated. This means that a light with no
more power than that produced by an ordinary electric light bulb becomes
intensely strong as it is concentrated to a pinpoint-sized beam.
3. Experiments with these pinpoint beams have shown researchers that
different energy sources produce beams that have a particular effect on certain
living cells. It is now possible for eye surgeons to operate on the back of the
human eye without harming the front of the eye, simply by passing a laser beam
right through the eyeball. No knives, no stitches, no unwanted damage--a true
surgical wonder. 4. Operations which once left patients
exhausted and in need of long periods of recovery time now leave them feeling
relaxed and comfortable. So much more difficult operations can now be
tried. 5. The rapid development of laser techniques in the past
ten years has made it clear that the future is likely to be very exciting.
Perhaps some cancers will be treated with laser in a way that makes surgery not
only safer but more effective. Altogether, tomorrow may see more and more
information coming to light on the diseases which can be treated
medically. Para 5 ______.