电影院放映厅的墙壁上都被装修成坑坑洼洼的,俗称“燕子泥”,其目的是为了( )
A:防止声音发生振动
B:减弱回声
C:增强回声
D:为了装饰剧场
X、Y、Z三种金属及化合物间发生如下化学反应:Y+2HCl═YCl2+H2↑Y+ZCl2═Z+YCl2X+ZCl2═Z+XCl2,X与稀盐酸不反应.则X、Y、Z三种金属的活动性由强到弱的顺序是( )
根据图画提示完成对话
Mike is a very cool boy. He very likes Chinese food. He likes ____, but he can't use ____. Mike's friend Wu Yifan lies ____. He can use ____ and ____now. Their teachers Miss White is beautiful . She likes ____and ____. She can use ____.
下列对动物特征的描述中,不准确的是( )
如图,△ABC中,D、E是BC边上的点,BD:DE:EC=3:2:1,M在AC边上,CM:MA=1:2,BM交AD,AE于H,G,则BH:HG:GM等于( )