删除复合条件的一行记录可以用如下语法：
db.test.remove({C_ID:"2"},1)
如果是分片环境
mongos> db.test.remove({CT1:"2"},1)
can only delete with a non-shard key pattern if can delete as many as we find : { CT1: "2" }
mongos> db.test.remove({C_ID:"2"},1)
mongos> db.test.remove({C_ID:"2"},1)
mongos> db.test.remove({C_ID:"2"},2)