“拉弗曲线”表明（）。 ["当税率为零时，税收为零","当税率达到最适点，税收达到最大","超过最适点，税率提高，税收减少","税率为100%时，税收降为零"]
土压式盾构开挖控制的项目不包含（）。 ["开挖面稳定","土压","排土量","盾构参数"]
方向阻抗继电器引入极化电压是为了消除（），在220KV线路保护中方向阻抗继电器记忆时间要求（）。
β值衡量的风险是（） ["系统性风险","非系统性风险","有时是系统性风险，有时是系统性风险","既不是系统性风险，也不是非系统性风险"]
On a cisco 1000 series controller-based access point，the alarm led is flashing red，but the other leds are off. What is this access point indicating？（） ["its ip address already exists.","it is operating normally.","it requires a code upgrade.","it has lost contact with the controller."]
按捻制次数分类，钢绳共有三种？
