circumstances 1 inability to obtain sufficient appropriate audit evidence
2 material mistatment if circumstance 1, is material give a qualify opinion, if material and also pervasive give a disclaimer opinion ie cannot express any opinion.
if circumstance 2 is material qualify opinion ‘except for’ if not only material but also pervasive give an adverse opinion ie the report is not true and fair. you will base your opinion after calculating materiality relative to either profit etc