渐尖、急尖、尾尖、钝尖、微凹、倒心形都属于叶的尖端形状的描述。
参考答案：对
电路有三种状态：处处连通的电路叫______；某处断开的电路叫______；______时电流很大，会烧坏电源．
用sometimes，sometime，some times或some time完成下面的句子
1.-Will you stay in Beijing for __________?
-Yes, I will.
2. __________ he goes to school by bike and __________ by bus.
3. The museum was built __________ before 1258.
4. After __________, Mr Liu came back from abroad.
5. He has been told not to play computer games too much __________.
