题目

--- ____________  does your father go to work? --- Five times a week. A．How long B．How soonC．How oftenD．How many times 答案：C解析:略请你观察图四，将鸡卵的结构和相应的功能用线连接起来：卵壳----为胚胎发育提供主要营养卵黄----进行胚胎发育的部位胚盘----提供胚胎发育所需的氧气气室----起保护卵细胞的作用．