a pocket calculator的用法和样例：
- I find a surplus store and buy a pocket calculator.
- I found a surplus store and bought a pocket calculator.
- PAUL Why don't you get him a pocket calculator?
- Mrs. Farias: I want to get a pocket calculator for your father.
- The basic British viewdata system uses an adapted TV set with a telephone connection and a remote control switch box that looks like a pocket calculator.