need做情态动词的时候否定可以连写吗？

当然可以 need表示“需要”或“必须”，作情态动词时，仅用于否定句或疑问句中，在肯定句中一般用must, have to, ought to,或should代替。如：
You needn’t come so early.
— Need I finish the work today?
— Yes, you must.
注意：needn't + 不定式的完成式“表示本来不必做某事而实际上做了某事”。如：
You needn't have waited for me.

当然可以。
当need作实义动词时否定形式则在其前面加助动词，如：don't /doesn't need

needn't=doesn't need to
You needn't go to buy sth.=you don't need to buy sth

可以的啊