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back pitch：背节距

back piece 背材 | back pitch 背节距 | back pitch 铆钉背距

back pitch：铆钉背距

back pitch 背节距 | back pitch 铆钉背距 | back plan 底视图

back pitch：橫節距(鉚接)

"齿背","back of tooth" | "横节距(铆接)","back pitch" | "后扶架","back rest"

back pitch：后节距

反位锁 back lock | 后节距 back pitch | 后廊期 back porch period

back and front pitch of awinding：绕组的前后节距

back and forth来回 | back and front pitch of awinding绕组的前后节距 | back and stopping trial倒车及停车试验

back and front pitch of a winding：绕组的前后节距

back and forth 来回 | back and front pitch of a winding 绕组的前后节距 | back and stopping trial 倒车及停车试验

back rest：靠背架

back projection 反射影 | back rest 靠背架 | back scatter constant 反向散射常数

back rest：座椅*背

Back pressure valve 背压阀 | Back rest 座椅*背 | Back shaft 后轴

back rest：座椅靠背

Back pressure valve 背压阀 | Back rest 座椅靠背 | Back shaft 后轴

back rest bracket：侯梁托脚

后梁 back rest | 侯梁托脚 back rest bracket | 后档 back rise

dioptric：折射光学的

dioptre 屈光度 | dioptric 折射光学的 | dioptrics 折射光学

Saturdays are fun：星期六很有趣

6. Saturdays are fun.星期六很有趣. | fun 为不可数名词,"快乐,有趣",在此做表语. | That must be fun. 那一定很有趣.