取得代理权的标志是获得代理证书，而代理证书通常表现为客户的（） ["正式授权","书面授权","公证授权","口头授权"]
Which constructs a BufferedIputStream？（） [" New BufferedInputStream（“in.txt”）；"," New BufferedInputStream（new File（“in.txt”））；"," New BufferedInputStream（Writer（“in.txt”））；"," New BufferedInputStream（new Writer（“in.txt”））；"," New BufferedInputStream（new InputStream（“in.txt”））；"," New BufferedInputStream（new FileInputStream（“in.txt”））；"]
由于化学氧化和细菌的联合作用，在矿区会产生严重的（）污染。
处理公共关系的六项原则。
Which is a valid identifier？（） [" false"," default"," _object"," a-cla"]
奶粉在奶糖中起着怎样的作用？
