实验I:反应产物的定性探究﹣﹣按如图装置(固定装置已略)进行实验:
中国终于有了自制的航空母舰,这确实值得骄傲。
China has owned its first homemade aircraft carrier finally. That's really something to be ____ ____.
若ab,c为实数,则下列命题正确的是 ( )