what 不能少,因为需要是主语从句,what不可以省略——(NOt accustomed to） ——speaking in public makes me very anxious.i will try my best to help him to overcome it 这一句答案用that he is not accustomed to 也是主语从句吗，that能省略吗？也是主语从句，这里that可以省略。因为上一句，i couldn't put up with需要加上宾语，what作为宾语在从句里是提前到句首了。而这句he is not accustomed to speaking in public 已经是完整的句子了，句首可以加that或者不加那为什么that he is not accustomed to==His not being accustomed to后面是什么结构？很He is not being accustomed to speaking in public是完整的主语从句，意思是他不习惯在公共场合说话，作为主语。整句的意思是不习惯在公共场合说话让我很紧张。