射极偏置电路如图所示，已知=60。(1)用估算法求Q点;(2)求输入电阻rbe;(3)用小信号模型分析法求电压增益Av;(4)电路其他参数不变，如果要使VCEQ=4V，问上偏流电阻为多大?

用于企业生产的某一类商品上，以区别于该企业生产的其他类商品的商标是()。

我国某型彩电的有效关税保护率为 12%，其原材料的进口关税为 5%，进口原材料价值占成品价值的 40%，那么我国该彩电的进口关税应为多少?(计算结果精确到 1%)

According to the "principles-and-parameters" theory, "principles" refer to highly abstract properties of grammar which are applied to language in general and which generate phrases and at the same time restrain the power of Move a, while "parameters" allow general principles to operate in certain restricted ways, according to which particular grammars of natural languages vary.

记录与社区居民健康有关的文件资料称为居民的（）