关于how much后面所接词汇的要求

关于how much后面所接词汇的要求
例句：I was impressed by how much he was eager to learn in class.这句话相当于在how much后面接了一个从句.个人认为how much 后面应该只能接名词性或形容词性的词,这句话应该改为 I was impressed
by how much eager he was to learn in class.不知道我的判断是否正确,还望高人不吝赐教,万分感激!
PS:原句并非摘自权威文献杂志,而是我一个同学写的,我跟他打赌这样写有问题,如果是我错了,还请告知how much后面都可以接哪些句子成分?越详细越好,在此谢过.