_______,  babies begin to talk between 12 and 15 months, but they can use body language to

communicate before they begin to speak. [ ]

A. In common  

B. In particular

C. In general  

D. In public

对热水采暖系统特点的描述，以下（）不正确。

A．散热器表面温度不甚高

B．室温容易保持均匀稳定

C．有热得快、冷得快的特点

D．较蒸汽采暖舒适感好