<b> a. He poses no more threat to me than his sister does.</b><br/><br/><b>b. He poses no more threat to me than does his sister.</b><br/><br/><b>c. We still need to be louder.</b><br/><br/><b>d. We need to be louder still.</b><br/><br/>All correct?<br/><br/>Which are preferred and why?<br/><br/>Thank you