1. 挂离合器：in force 有效 | in gear 挂离合器 | in layers 成层

2. 齿轮连上：in fun 开玩笑 | in gear 齿轮连上 | in general 通常

3. 齿轮已与机器联接正常：in gate 输入门 | in gear 齿轮已与机器联接正常 | in gear 齿轮已与机器联结正常

4. 齿轮已与机器联结正常：in gear 齿轮已与机器联接正常 | in gear 齿轮已与机器联结正常 | in geographical rotation 按地理次序

adj

1. having gears engaged

e.g. the car is in gear