请用must和haveto来代替下列带括号的部分.
shesaid(itwouldbenecessaryforusto)stayhere.
(itisnecessaryformeto)havesomehelp.
(itwasbenecessaryforhimto)gooutlastnight.
对他来说昨晚出去是必要的
hemusthadgooutlastnight
imusthadhavesomehelp
shesaidwehavetostayhere
对么不懂一定要说明
并说明为什么