根据短文理解，从A、B、C、D四个选项中选择最佳填空。

    Hi, my name is Dave. I'm 8 1 old. My birthday is 2 December 12th. I have 3 birthday party every year. Today I have my 4 birthday party. I get some gifts at the party. 5 are very good and I really like them. This 6 T-shirt is from my mother. Green is my 7 color. My mother buys me a pair of green 8, too. My father buys some 9 about history for me, because I like 10 best. I think these books 11 very interesting. My grandparents 12 I like playing basketball, 13 they buy me a basketball. I can 14 it with my friends after class. I'm very happy today.

    15 is your birthday, my friend? Do you have a party, too?

如图所示，两平行金属板A、B板长L=8cm，两板间距离d=8cm，A板比B板电势高300V，一带正电的粒子电量q=10^﹣10C，质量m=10^﹣20kg，沿电场中心线RO垂直电场线飞入电场，初速度v₀=2×10⁶m/s，粒子飞出平行板电场后经过界面MN、PS间的无电场区域后，进入固定在O点的点电荷Q形成的电场区域，（设界面PS右边点电荷的电场分布不受界面的影响），已知两界面MN、PS相距为12cm，O点在中心线上距离界面PS为9cm，粒子穿过界面PS最后垂直打在放置于中心线上的荧光屏bc上．（静电力常数k=9×10⁹Nm²/C²）

【甲】晏子至，楚王赐晏子酒，酒酣，吏二缚一人诣王。王曰：“缚者曷为者也？”对曰：“齐人也，坐盗。”王视晏子曰：“齐人固善盗乎？”晏子避席对曰：“婴闻之，橘生淮南则为橘，生于淮北则为枳，叶徒相似，其实味不同。所以然者何？水土异也。今民生长于齐不盗，入楚则盗，得无楚之水土使民善盗耶？”王笑曰：“圣人非所与熙也，寡人反取病焉。”【乙】刘凝之，字志安，小名长年，南郡枝江人也，父期公，衡阳太守，兄盛公，高尚不仕。凝之慕老菜、严子陵为人，推牢财与弟及兄子，立屋于野外，非其力不食。州里重其德行。州三礼辟西曹主簿，不就，妻梁州刺史郭铨女也，遣送丰丽，凝之悉散之亲属。妻亦能不慕 荣华，与凝之共安俭苦。

（选自《宋书》，有删改）