你好！首先看一下什么是一般疑问句：
一般疑问句是疑问句的一种。它是指用yes（是）或no（否）来回答的句子。其结构是：
系动词be/助动词/情态动词+主语+其他成分
通常回答为：
肯定：Yes，+主语+提问的助动词.
否定：No，+主语+提问的助动词+not.
如:
Are you from Japan﹖
Yes I am． / No I'm not．
1．将陈述句变为一般疑问句时，如句中有be 动词（am/ is/ are）时，可直接将它们提至主语前。如主语为第一人称，应将其改为第二人称。如：
I'm in Class 2Grade 1． →
Are you in Class 2Grade 1﹖
We're watching TV． →
Are you watching TV﹖
2．陈述句中有情态动词（can、may、must …）时，也可直接将它们提至主语前，即可成为一般疑问句。如：
He can swim now． →
Can he swim now﹖
The children may come with us． → May the children come with us﹖
3．陈述句中只有一个实义动词作谓语且其时态为一般现在时，变为一般疑问句时要在句首加do或does 主语后的实义动词用原形。如：
I like these animals． →
Do you like these animals﹖
She wants to go to the movies． → Does she want to go to the movies﹖
4．一般疑问句一般读升调(↑)
5．一般疑问句有时不用yes或 no 回答。如：
Are they in town now﹖
I think so.
May I sit here﹖
Certainly．
Does he like soccer﹖
Sorry I don't know．
综上所述：将They were here just now.改为一般疑问句为：Were they here just now?
书山有路勤为径，学海无涯苦作舟
==========与君共勉=========
温馨提示：答案为网友推荐，仅供参考