【单选题】John promised he ________ the Great Wall with us.
【判断题】某控制系统采用气动调节阀,要求气源中断时关闭阀门以保证安全,则应该选用气关阀。
【单选题】Last Monday, John promised that he ________ today, but he hasn't arrived yet.
【单选题】在下列串联矫正的装置中,能够在w_c=1处提供最大相位超前角的是
【判断题】某控制系统采用气动调节阀,要求气源中断时切断阀门以保证系统安全,则应该选用气关阀。
【单选题】John promised his doctor he _____ not smoke and he has never smoked ever since.
【单选题】John promised his doctor he___not smoke.
【判断题】某控制系统采用气动调节阀,要求气源中断时却断阀门以保证系统安全,则应该选用气关阀。( )