橡胶是一种重要的战略物质,一般分为天然橡胶和合成橡胶两类。丁苯橡胶是合成橡胶的一种,其结构简式为:
下列说法正确的是( )
A:它的单体是
B:丁苯橡胶是CH2=CH-CH=CH2和 通过缩合反应制得的
C:装液溴或溴水的试剂瓶可用丁苯橡胶作瓶塞
D:丁苯橡胶会老化
Hello, my name is Tom. I have P.E , art and English on Tuesday(星期二).It is my favourite day. I like English. Look, that is my math teacher. He is very short and kind . His name is Wang Lin. I like beef very much , but I don't like apples . I like bananas , too.
有指向标的地图,指向标箭头指向一般为( )
“我在长安街上碰到一个拿起电话来打个没完没了的人”可缩写成“我碰到人”。( )