?成直角
... 脉冲 impulse; pulse; impulsion; out-burst; pip (荧光屏上的) 一个光脉冲 a pulse of light; 一个声脉冲 a pulse of sound; 一个压力脉冲 a pulse of pressure; 在低频率(譬如每秒十次)时, 所感觉到的是脉冲而非振动。 at low frequencies, such as 10 per sec., pulsation is sensed rather than vibration 成直角 on the square; perpendicular; square to 垂直角 rigth angle; vertical angles; verticalangle ...