B

    I'm Tom and I like sports. Basketball is my favourite. I play it in. my school in the morning. My school is big and there is a playground and a sports hall in it. Every morning, many teachers and students play sports in the playground. I play there with my friends too. When the weather is bad we play in the sports hall. It's on the left of the playground. Now I'm in the sports hall but I don't play basketball. Some students from London are in our school and I'm their guide (导游).

    My family also like sports too. My parents kick(踢)jianzi near our home every morning. My sister Mary plays table tennis with her classmates in their school. It is small but beautiful.

把一团光亮的细铁丝塞入大试管中，将试管倒插水中后再固定好（如图），放置足够的时间(约一周，室温不变)后，观察到铁丝表面有____生成，试

管内水面将____ (填“上升”、“下降”或“不变”)，此时试管内的压 强____ (填“大于”、“小于”或“等于”)大气压。

  30的所有的因数的和是____

如图，正方形网格中的每个小正方形边长都是1，每个小格的顶点叫做格点，以格点为顶点分别按下列要求画三角形．

如图，四边形ABCD中，AB=AD=CD=1，BD=$\sqrt{2}$，BD⊥CD．将四边形ABCD沿对角线BD折成四面体A′﹣BCD，使平面A′BD⊥平面BCD，则下列结论正确的是（　　）