A：大多数抗原直接刺激B淋巴细胞，使之增殖、分化并产生淋巴因子
B：切除小白鼠的垂体后，其血液中促甲状腺激素释放激素增加
C：细胞分裂素的主要作用是促进细胞分裂
D：激素种类多，量极微，既不组成细胞结构，又不提供能量，也不起催化作用
完形填空
Mother's Day is a time of commemoration (纪念) and celebration for Mom. It is a time of breakfast in bed, family gatherings, and crayons scribbling "I Love You".
The earliest Mother's Day celebrations can be dated (1) to the spring celebrations of ancient Greece in honor of Rhea, the Mother of the Gods. During (2) , England celebrated a day called "Mothering Sunday". "Mothering Sunday" honored the mothers of (3) . In the United States Mother's Day was first suggested in 1872by Julia Ward Howe. In 1907, Anna Jarvis, from Philadelphia, began a campaign (运动) to establish (建立) a (4) Mother's Day. Ms Jarvis persuaded (说服) her mother's church in Grafton. West Virginia to celebrate Mother's Day on the second anniversary (周年纪念日) of her mother's 55 , the 2nd Sunday of May. And the next year Mother’s Day 56 in Philadelphia. Ms Jarvis and her supporters began to 57 officials, businessmen, and politicians in their quest to establish a national Mother’s Day. It was successful. 58 1911 Mother's Day was celebrated in almost every 59 . President Woodrow Wilson, in 1914, announced Mother's Day as a national holiday that was to be held on the 2nd Sunday of May each year.
While many countries of the world celebrate their own Mother's Day at 60 throughout the year, there are some countries such as Denmark. Finland, Italy, Turkey, Australia, and Belgium which also celebrate Mother's Day on the second Sunday of May.
