用科学记数法表示﹣0.0000064记为( )
A:﹣64×10﹣7
B:﹣0.64×10﹣4
C:﹣6.4×10﹣6
D:﹣640×10﹣8
按要求补充句子。
- What is this? - It is a ____.(鸟)
What was the weather like in the mountains yesterday?
唐朝进入全盛时期是在( )