读一读,连线。
①What can you see?____ A. It's green.
②What colour is it?____ B. OK, Mum.
③Put the box on the desk. ____ C. Yes, please.
④Chopsticks?____ D. I can see a slide.
如下图所示的电路,断开开关S1、S2,闭合开关S3,灯L1与L2____ 联;断开开关S3,闭合开关S1、S2,灯L1与L2____ 联。(填“串”或“并”)
如图所示,一架澳大利亚的飞机在其国内航线上飞行,可判断( )