在显微镜下观察洋葱鳞片叶内表皮细胞和人的口腔上皮细胞时,都能看到的结构是( )
A:细胞壁
B:叶绿体
C:细胞核
D:液泡
能说明铁丝在氧气中燃烧是化学变化的主要实验现象是( )
如图,2013年12月14日,我国发射“嫦娥三号”探测器,进行首次月球软着陆和自动巡视勘察.
请根据所听到的内容,选择表格中的正确信息,用5—6句话进行复述。
(将复述内容写下来)。
⑴ How about studying abroad in recent years? (enjoyable/popular)
Advantages
⑵ What's the first advantage?
(make more friends/experience foreign life)
⑶ What's the second advantage?
(improve their foreign languages/learn about different cultures)
Disadvantages
⑷ What's the first disadvantage?
(too young to look after themselves/too young to learn)
⑸ What's the second disadvantage?(the low cost/the high cost)
你可以这样开始:The speaker is talking about…
Answer:____
如图,在△ABC中,D、E分别是AB、AC的中点,过点E作EF∥AB,交BC于点F.
(1)求证:四边形DBFE是平行四边形;
(2)当△ABC满足什么条件时,四边形DBFE是菱形?为什么?