whistle a tune的用法和样例：
- He even began to whistle a tune under his breath.
- The boy was whistling a tune merrily.
- Miss Ophelia thought she had said enough, and therefore sat silent. St. Clare whistle a tune.
- Whistle a tune.
- "Go ahead!" So down came an arm. Little John began whistling a tune.
- A small boy was beating out a tune on a tin can.