—I've got some .
—Great! I'd like to write with it.
—Do you have enough nurses to take care of the injured?
—No, I think we need _______ nurses.
李明同学做了如下实验:取标号为A,B,C的三支试管,各加入2毫升稀淀粉糊,然后将这三支试管放入37.5℃水浴锅中,15至20分钟后,各滴3滴碘液.下列关于这个实验的表述正确的是( )