课文填空请根据所学 课文原文 填写空缺处的单词 (共20个空格；每空0.5分，满分10分)

课文填空请根据所学 课文原文 填写空缺处的单词 (共20个空格；每空0.5分，满分10分)
Aspirin was invented in 1897. However, the __小题1:___ chemical used to make aspirin can be found in nature. Nearly 3,500 years ago, people __小题2:__ on leaves or drank a kind of tea made from leaves ___小题3:__ a special chemical to reduce body pains and __小题4:___.
It was in 1897 that a __小题5:___ chemist called Dr Felix Hoffmann produced aspirin from this chemical. The first ___小题6:__ of this medicine took place in 1899, when the company Hoffmann worked for began ___小题7:__ the medicine in powder form to physicians to use with __小题8:___. A year later, in 1900, aspirin was sold in shops in the form of __小题9:___.
However, a recent survey __小题10:___ in the USA shows that 80 per cent of Internet users __小题11:___ it mostly to search for answers to questions. The second most common use of the Internet, for 79 per cent of Internet users, is to find out information about __小题12:___. These statistics __小题13:___ that gathering information is the __小题14:___ use for the Internet.
Another truly wonderful __小题15:___ of the Internet is the way people use it to build social ___小题16:__. One of the greatest benefits of Internet friendships is that they are __小题17:___ on common interests, rather than ___小题18:__ or age. Young people from __小题19:___ backgrounds and different countries can form friendships that will last their __小题20:___ lives.