间接一般疑问句 do you think that 和 do you think if 的区别

间接一般疑问句 do you think that 和 do you think if 的区别例如：Do you think that this kind of accident is acceptable?Do you think if this kind of accident is acceptable?表达的意思都一样么,表达方式都正确么,请高人指教,上面两个句子算是间接一般疑问句么，另外例如：I want to know if this kind of accident is acceptable.只有这样的句子才是间接一般疑问句吗？