短文填空

     Have you ever tasted or perhaps heard of sugar painting? As fewer people choose to make this kind of painting, the traditional Chinese folk craft might have become a ____(distance)memory in some ways.____, a 38-year old craftsman, Li Jianzhong, is committed to____(keep)the art of sugar painting alive.

     Li worked as a miner for more than ten years. After ____mine closed down, Li turned to housing decoration, until he ____(force) to give that up due to a finger injury. Earlier this year, he discovered sugar painting, something he really had an interest in and a strong desire to learn.

     Since there was no sugar painting craftsman in his village, he studied by ____(he) through large quantities of videos and information on the internet. Li loved painting when he was young, and he found it easy____(learn) the skill in sugar painting. He soon mastered the skill and could make a ____(vary) of sugar paintings. A sugar painting is made with melted brown or white sugar. Craftsmen ____(normal) paint animals and flowers on a stone board with the syrup(糖浆). When the sugar cools down, ____appears is a piece of sugar art.

有学者认为，《天朝田亩制度》在晚清思想史中具有独特性，显示了传统思想里从未有过的一种组合，即“财产共有与权力全面控制的组合”。在这种思想的“组合”过程中，没有对其产生影响的是（    ）

如图所示，自行车的车轮半径为R，车轮沿直线无滑动地滚动，当气门芯由轮子的正上方第一次运动到轮子的正下方时，气门芯位移的大小为（   ）

海洋是个极有开发潜力的资源宝库。研究海洋，开发利用海洋，常常需要潜入到海洋的深处去，潜水艇是人类研究海洋的重要设备，它的上浮和下潜是通过改变____来实现的，当潜水艇潜到水下500m深处时，它受到水的压强是____pa。

已知数列$\left\{a_n\right\}$的前n项和为$S_n$，且$a_1=-10,a_{n+1}=a_n+3\left(n\in N^{*}\right)$，则$S_n$取最小值时，n的值是（   ）