危险化学品安全技术
用球磨机研磨具有爆炸性的物料时,球磨机内部需衬以橡皮等柔软材料,同时需采用( )。
A.石球
B.铁球
C.钢球
D.青铜球
参考答案:D
同义句转换。
1. The radio went wrong yesterday.
____________________________________
2. They were injured in the accident.
3. He can't memorize all the words in 20 minutes.
4. You can watch TV after finishing your homework.
5. Unless you keep ice cream in a fridge, it melts.
下列不是板层白内障的临床特征的是()
A.是儿童期最常见的白内障
B.表现为晶状体中央的盘状混浊
C.视力减退不明显
D.瞳孔散大后,视力增进也不明显