下列油漆施工中,一般不需要抛光剂的是( )。
A.木基层混色磁漆磨退 B.木基层施涂清漆C.木基层施涂硝基清漆磨退 D.木基层施涂丙烯酸清漆磨退
参考答案:B
It is on 1st Sept. _____ students go back to school every year. [ ]
A. when
B. that
C. who
D. what
为了使HCl气体被水溶解,最合适的实验装置是(图4-4)()
图4-4