teaching is as much an art as it is a science.

翻译为：

人们普遍相信教学和科学一样是一门艺术.


as...as...中间可以接adj./adv.的原行,也可以接名词,

结构如下：as + much+a/an+n.(可数名词单数)+as...

1、【that teaching is as much an art as it is a science】主语从句（后置）,it是形式主语.

2、as much an art【 as it is a science 】比较状语从句作much的程度状语.

3、【试译：】人们普遍认为,教学是一门科学,更是一门艺术.

参考资料：http://zhidao.baidu.com/question/303814952.html

as much as和...差不多，一样
可以看成两个句子teaching is an art & it(代teaching)is a science
所以主谓还是不能少
教学既是一门艺术，也是一门科学。