need什么时候用情态动词,后面加动词原型.THese windows need____.Can you do them?A claenB cleaning我本身知道need,want等词后面＋ing 主动表被动.ing＝ to be done.但need又有情态动词的意思,如果是情态动词后面应该加动原.如何区分?

need to do时做情态动词 ，need doing是被动语态。

need to do
need doing一般就是这2种用法 具体用什么形态 要结合文章内容来判断 还要看所给词所在句子的意思

need doing 是用v-ing来表示被动,某物需要被怎样,比如 The desk needs repairing.
need to do 是是主动,主语常是某人,某人需要做什么,比如 I need to do the homework now.
以上两种情况下need都是行为动词.
need做情态动词时后面不跟不定式而是直接跟动词原形.
最主要的区别是：need表示主动含义时,肯定句中常做行为动词,也就是加to do. 如: I need to do my homework now.
否定和疑问句中常做情态动词,加动词原型,否定直接加NOT, 疑问直接提前.
如： Need I tell him the new?
You need not tell him the news.

一般情况下,need用于否定句和疑问句时用作情态动词
在肯定句中作实义动词.
而且,need 和want可以接主动的不定式作宾语.need doing =need to be done.
所以,本题1.是肯定句,need用作实义动词
2.need cleaning =need to be cleaned
选B