【单选题】—When you have difficulty , do remember to_________. Two heads are better than one.
【单选题】如图所示电路,若以 A 点作为参考点, X 点的电位为 5 V ;若以 B 点为参考点, X 点的电位为 10 V ,则 U AB = ( ) 。
【单选题】汽车的日常维护作业,主要是由( )来执行。
【单选题】在电路中若测得Uab=20V,则a、b两点中()电位高。
【判断题】使用空气压缩机时,应随时注意压力计的指针,不能使其超过极限红线。
【单选题】—What do you think of the two students ________ to take part in the competition? —They are hardworking as well as intelligent.
【简答题】Do you know what lungs (肺) are like? (11) are in the upper part of our bodies. We have two of them. There are thousands of little pipes (管子) going through them. The (12) are like the branches of a tre...
【简答题】若电路中 A点的对地电位是 15 V,B点的对地电位是 20 V,则U BA =________ 。