在装载高度超过（）的货物上，通过道口时严禁坐人。A、二米 B、三米 C、四米 D、五
题型：单项选择题
问题：
在装载高度超过（）的货物上，通过道口时严禁坐人。
A、二米
B、三米
C、四米
D、五米
题型：单项选择题
| 判断下列句子是否符合短文内容，符合的用“T”表示，不符合的用“F”表示。 |
| The elephant is another animal that lives in groups. An elephant herd (群) usually has from twenty to forty members. The elephants in the herd depend on one another for help in time of trouble. |
| The leader of the group is usually a wise and strong female. She travels at the head of the herd and is followed by the other females and their young. The bull elephants (公象)follow last. When danger threatens(威胁), the bulls form a circle around the weaker animals and guard (守卫) them. The members of the herd are loyal to (忠诚) one another. A sick or wounded elephant is not left behind to die. If an elephant is sick, the whole herd stops traveling until it gets well. When an elephant is injured, two others walk on both sides of it and support it with their bodies. A member of the herd may be caught in a trap. Then the others try to free it. |  |
| Elephants are fond of the youngsters in the group and give them special care. They help young animals stay afloat (漂浮着) when the herd crosses a river. They work together to rescue a calf (幼象) that has wandered (迷路) into a dangerous place. A female elephant that is about to give birth to (生产) her young leaves the herd for a short time. However, she takes another female along to act as "aunt". The aunt stands guard and helps the mother with her new-born calf. In this way, the whole herd protects its newest member. ( )1. The leader of the elephants travels in the middle of the herd. ( )2. In times of danger, the males form a circle around the weaker animals. ( )3. The leader of an elephant herd is usually a strong female. ( )4. Sick elephants are usually left behind to die. ( )5. Elephants will try their best to save the young ones when they are in dangerous situations. ( )6. Elephants can help each other in time of trouble. ( )7. A strong elephant can carry a sick elephant on its back. |
键和
键数目之比为________，B、C、E三种元素的第一电离能由大到小的顺序为_________(用实际元素符号表示)。
离子中B原子轨道的杂化类型为__________。
。该晶体的密度为________
g(NA表示阿伏加德罗常数，E的相对原子质量为b)。