心皮是由大孢子叶两边愈合进化而来的.It has evolved by fusion of the two edges of the megasporophyll.孢子异型:指植物产生两种大小不同的孢子: 小孢子和大孢子.Heterospory The production of two different sizes of spore: microspores and megaspores.通常较大的大孢子含有更多的贮藏养料.The ...
She then decided right before the opening to make a dramatic announcement.然后就在开幕式开始之前，她决定要宣布一件激动人心的事情。He was floored by the announcement.这个通告使他不知所措。The announcement was greeted enthusiastically.公告受到人们的热烈欢迎。...