self-propelled gun的解释
1. 自行火炮：射钉枪:nail-shotting gun | 自行火炮:self-propelled gun | 平衡炮:gun for balance
2. 自走炮：自动车 self-propelled car | 自走炮 self-propelled gun | 自走式收割脱 self-propelled type combine