hear用法：）~~
常用的词组有：
（1）hear sb do sth 听到某人做某事
hear sb do sth 可以是指经常听到
hear sb doing sth听到某人正在做某事.
（2）hear sb doing sth 听到某人一直（包括现在）在做某事
举例：
Where”s mary now ? Do you know ?
- No,but I heard _____ in her room a few minutes ago.
- A her singing B her sing C she was singing D all the answers are right
分析：选B,hear sb do sth 听到某人做某事