寻呼系统经常对民航频率造成干扰的原因之一是寻呼频率正好落入民航频段中。
参考答案：错
根据句意，用首字母适当的形式填空。
1. It's cold now. please put on your s_______.
2. In summer Bill likes to wear s______, and Helen likes to wear skirt, too.
3. How ______ are the pants? It's 30 dollars.
4. You cant' run fast without a pair of s_______.
5. Do you know that old man with a black h_______ over there?
胞质杂种与体细胞杂种在核的组成上往往有明显区别，用哪些方法可以鉴别？
