题目

Win a week in England! You still don’t know what to do this summer? Well, here’s your chance to win a one-week language course in Kent, England! Free4Fun and ETC (English Travel Connections) are giving  away two trips to Rochester. This historic city is less than an hour’s drive from London and close  to the sea resort of Herne Bay. It is also the home of one of England’s most famous writers,  Charles Dickens. The town of Rochester is in Southeast England. Charles Dickens often wrote  about it in his books. His home, Gad’s Hill, is there, too. A popular attraction is Rochester在离体的植物器官、组织或细胞形成愈伤组织的过程中，下列哪一项是不需要的A．消毒灭菌 B．适宜的温度C．充足的光照 D．适宜的养料和激素