1,本题的意思是 叫喊,大声地说.他大声对孩子们叫喊,把球扔回了银行
类似的用法：He called out to his father for help.call out 还有其他意思：调来; 请去
The fire brigade was called out twice last night.召集 The teacher called out his students.等等.
2,experience做经历讲时是可数.比如你去过几次北京.2-3次,这样就是可数了.
当做经验时是不可数,如：teaching experience.教学经验.
depth 做 n.深,深度,纵深 讲时是不可数.What is the depth of this lake?
这个湖有多深?
做深处,深渊 讲时,是可数
The old man disappeared into the depths of the house.
老人消失在住宅深处.
3,competence 能力,技能
We knew her competence in solving problems.
我们都知道她解决问题的能力
总之,一般来说,如果是抽象名词的话,均为不可数名词.
希望对你有用.