下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。
增加：在缺词处加一个漏字符号（∧），并在其下面写上该加的词。
删除：把多余的词用斜线（＼）划掉。
修改：在错的词下划一横线，并在该词下面写上修改后的词。
注意：1．每处错误及其修改均仅限一词；
2．只允许修改l0处，多者（从第ll处起）不计分。
Ask your friend that he can use a glass of water as a musical instrument．Of course, he can’t．Then you take a glass of water．You put your finger in water and then move it slow round the rim of the glass, as shown in the picture．Your finger must not be much wet, but it must not be dry．So you must try many time．At last you will hear clear music which comes from the glass．When your finger moves round the rim, it makes the glass to vibrate and the glass makes a musical voice．The same principle makes the violin or its strings give music．
The America scientist Benjamin Franklin made a musical instrument out of glass bowls．He used the different principle．