骨料的级配是指混凝土中骨料的()。A.不同粒径颗粒所占比例的分布情况  B.占10%

根据短文内容，选择最佳选项。

     One day Ram was lost on his way home and went into a forest (森林). He walked in the

forest and saw a den (洞穴). He went inside and saw a lion there. He was scared and ran out of

the den. At that time, an elephant came and said, "Don't worry. I will be your friend." Great!

Could you tell me the way out of the forest?" asked Ram. But the elephant did not know the

way. They walked and walked until the elephant was trapped (被捕获) in a cage (笼子) that a

man put for him. To save the elephant, Ram asked all the animals in the forest for help, but

they could do nothing. At last, when the man slept, Ram took the key from his bag and opened

the cage. The elephant thanked Ram very much. He called other elephants and trumpeted (吼叫) with them. Hearing the sound, some people came to the forest and took Ram home.

1. What did Ram see in the den?

A. A tiger.

B. A man.

C. A lion.

D. An elephant.

2. What does the underlined word "save" mean?

A. Turn on.

B. Make friends with.

C. Keep (money).

D. Keep someone safe.

3. How did Ram finally get out of the forest?

A. He found the way home.

B. Some people took him home.

C. His parents found him in the forest.

D. A friend of the elephant took him out.

4. Which of the following is TRUE according to the story?

A. Ram was trapped in the den.

B. Ram was lost when he went to school.

C. No animals could help the elephant out of the cage.

D. Ram asked the man for the key and opened the cage.

5. This is a story about _____.

A. a boy and a lion.

B. a boy and an elephant

C. an elephant and a lion

D. an elephant and his friends

什么情况下发生药物的相互作用？（）

A.在药物的吸收过程中有可能发生药物的相互作用

B.在药物的代谢过程中有可能发生药物的相互作用

C.在药物的排泄过程中有可能发生药物的相互作用

D.仅在药物的代谢过程中有可能发生药物的相互作用，其他过程不会发生药物的相互作用

E.仅在药物的吸收过程中有可能发生药物的相互作用，其他过程不会发生药物的相互作用

质量为1kg的物体被30N的水平压力压在竖直墙上静止不动，如图所示，则此物体对墙壁的压力是多大？墙对物体的支持力为多大？若水平压力减小为20N，此时物体恰好匀速下滑，则物体受到的摩擦力是多大？方向如何？（取g=10N/kg）

根据下列图示，回答与铁有关的问题。

（1）图A为铁元素在元素周期表中的相关信息，可知铁的相对原子质量为

（2）图B为铁原子结构示意图，其中x的数值为       ；

（3）图C为地壳中某些元素的含量（质量分数），其中含量最多的元素与铁元素组成的化合物的化学式为       （写出一种即可）。

水蒸汽蒸馏的原理是什么？