1. 兼饰两角：double arch bridge 双曲拱桥 | double as 兼饰两角 | double back 对折

2. (演员)兼演(另一角色)：see double 将一物看成两物, 眼睛发花(尤指酒醉时) | double as (演员)兼演(另一角色) | double back 向后折; 把...对折 往回跑

3. 兼演(角色),兼作：They told us the do's and don't in the letters. 他们在信中告诉了我们该帮啥,不该做啥. | double as兼演(角色),兼作??????: | The director doubled as the actor. 导演兼演员.