It's 11: 00 pm now, but the light in Peter's room is still on. He must have forgotten _______ before going to bed.
分别标有 "220V 20W" 和 "220V 100W" 字样的甲、乙两盏电灯,若将它们串联起来仍接在 220 V的电路中,则下列判断中正确的是( )
①种皮 ____ A、储藏养料
②胚 ____ B、保护胚
③胚乳 ____ C、能发育成新植株