杂交种含有的基因组合是自然群体中所不存在的。
参考答案:对
根据句意和汉语或首字母提示,填写单词。
1. He wrote down his name on the _____(石头).
2. The soft-hearted old man wouldn't hurt an _____(蚂蚁).
3. We have five f on each hand.
4. He is not strong enough to l the heavy box.
5. There's a delicious s coming from the kitchen.
简述信息传递的主要媒介。