都是填空题,没有上下文,1.He didnt go into detail on the subject;he spok

都是填空题,没有上下文,
1.He didnt go into detail on the subject;he spoke in particular请问为什么用in particular 不用in general?
2.Now that we have all the materials ready,we should begin the new task at once.为什么用Now that,不用Since now?
3.She refused to DOWN the car keys to her husband until he had promised to wear his safety belt.这里怎么可以用DOWN?
4.There is a real possibility that these animals could be frightned,should there be a sudden lous noise.请解释下shold there be的用法,为什么要这样用?
down难道可以做动词？