-- May I take this book out?
-- No, you ______.
A：can't
B：may not
C：needn't
D：aren't
仔细读课文《“没头脑”和“不高兴”》，说说这篇课文给我们什么启示？
The manager is busy at the office; you'd better leave him ________.（ ）
鸟卵的结构中含有细胞核的是____，既能提供养料又能提供必需的水分的是 ____。
A、胚盘 B、卵黄 C、卵壳 D、卵白．
