The present invention relates to a method of preparing a composition comprising mixing a silica sol having an S-value from about 5 to about 50% and a mineral acid.
本发明涉及制备组合物的方法，该方法包括将S值为约5％至约 50％的硅溶胶与无机酸混合。
Orff′s music teaching method has greatly reduced the difficulties of music education. Kids at the age of 4 or 5 can play the tune of a famous song after they have heard it once or twice.
奥尔夫的音乐教学法把音乐教育难度降到最低限，一首世界名曲，四五岁儿童听一到两遍便可准确地用打击乐器演奏。
Orff′s music teaching method has greatly reduced the difficulties of music education. Kids at the age of 4 or 5 can play the tune of a famous song after they have heard it once or twice.
奥尔夫的音乐教学法把音乐教育难度降到最低限，一首世界名曲，四五岁儿童听一到两遍便可准确地用打击乐器演奏。
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