题目

Jim and Steve were twins. They played on the same football team, and shared all the same toys, the same bedroom and the same friends. They shared ________.One Sunday, Jim and Steve went ________ to ride their blue bike, but they wanted to go to different places. Their mother heard the two boys arguing and came outside. She told ________ to take turns to ride the bike. However, they didn't want to share it.A few days later, their mother brought a pet ________ home for the boys. Can't we each have our own cat? asked the boys angrily. They were ________ of sharing everything.I'm sorry, but you mu下列操作中，能鉴别空气、氧气和氢气三瓶气体的是 A．插入燃着的木条             B．观察气体颜色 C．倒入澄清石灰水             D．闻气体的气味