根据Rules Of Games里Alter Self中的解释：
You retain all extraordinary special attacks and qualities derived from class levels.
As noted in Part One, extraordinary special attacks or qualities from class levels are primarily a function of the mind (you acquired them through experience and training), so you can keep right on using them when you're in an assumed form.
You lose extraordinary special attacks and qualities not derived from class levels.
Also as noted in Part One, extraordinary special attacks and qualities are assumed to be largely a function of your body. When you change your body with the alter self spell, you lose the special physical adaptations that make those extraordinary special attacks and qualities.
You retain your spellcasting abilities, but your assumed form might limit what you can do.
You can use spells with verbal components only if you have retained the ability to speak. You can use somatic and material components only if your assumed form has limbs capable of dealing with them.
又根据Polymorph的This spell functions like alter self
和Shapechange的This spell functions like polymorph
加上以上Skill William的规则精神解释
毫无疑问，Shapechange不会让受术者失去自身的职业能力
