【简答题】The superstars debuted in late 1980s including ______.
【简答题】复合按钮按下时,触点通断情况是 A 、常开触点先闭合,常闭触点后断开 B 、常闭触点先断开,常开触点后闭合 C 、常开触点先闭合,常闭触点后断开 D 、常闭触点断开与常开触点闭合同时
【单选题】Why did saccharin have a bad name in the late 1970s and early 1980s?
A.
Because saccharin contains no calories.
B.
Because some people developed cancer after taking saccharin.
C.
Because saccharin was reported to have caused cancer in lab animals.
D.
Because saccharin tastes bad.
【判断题】按下复合按钮时先断开常闭触点,然后接通常开触点 ;当 释放复合按钮 后, 先断开常开触点,再接通常闭触点 。
【判断题】按下复合按钮时,常开触点先闭合,常闭触点再断开
【判断题】按下复合按钮时,常开触点先闭合,常闭触点后断开
【单选题】关于对空调制冷原理的描述,下面正确的选项是( )。
B.
空调热交换器中,蒸发器是用来散热的,冷凝器是用来吸热的;
C.
空调压缩机润滑油的牌号越大,粘度越小,凝固点越低;
【简答题】空调压缩机润滑油的牌号越大,粘度();凝固点()。