aerospace-to-ground observation technology的用法和样例：
- The fox went to ground under a rocky escarpment.
- I have to grind the knife; it is blunt.
- He managed to grind out a few lines.
- He has gone to ground in his country estate to avoid awkward questions.
- Since Mr.Cramer is a traveling salesman, he's often difficult to run to ground.
- The enemy was forced to ground arms.