量角器可以测量（ ）的大小，单位是（ ）。

阅读短文，选择正确答案。

       Let me tell you something about our park. It's not big but beautiful. Here is the gate. On the right of it.

There are two toilets. There is a shop on the left. There is a big tree beside the shop. In the middle of the park,

there is a playground. Many lovely boys and girls have a good time there. Some are flying kites, and others are

dancing. They are really happy. Is there a lake in the park? Of course. It is big and pretty. It is beside the

playground and there are many boats on it.

1. How is the park? It is ________. [ ]

A. big

B. beautiful

C. lovely

D. happy

2. Where are the toilets?[ ]

A. On the right of the gate

B. On the right of the park

C. On the left of the gate

D. On the left of the park

3. We can see a shop ________.[ ]

A. beside the lake

B. in the middle

C. on the left

D. on the right

4. Is there a lake in the park? ________. [ ]

A. No, it isn't

B. Yes, it is

C. No, there isn't

D. Yes, there is

5. Are the boys and girls happy? [ ]

A. Yes, we are

B. Yes, you are

C. Yes, they are

D. No, they aren't

有一串单项式：x，-2x²，3x³，-4x⁴，5x⁵，…，19x¹⁹，-20x²⁰，…，则第100项是______，第n项是______．

焦炉煤气的主要成分是CH4。

根据《建筑基坑支护技术规程》4.8.8要求，当支护结构的安全等级为一级时，抗拔承载力检测值与轴向拉力标准值的比值≥（）。

A.1.1

B.1.2

C.1.3

D.1.4