缺胶
参考答案：
外胎、内胎、垫带表面胶量不足而出现的凹陷现象。
Many new workers ________ and after six months they will be sent to build a new railway.[ ]
A. are being trained
B. are training
C. will train
D. will be trained
客户机/服务器(C/S)结构是一种基于 【11】 的分布处理系统。
