如果一个三角形的两条边分别是40cm和60cm，第三条边的长度要在下面的三个量中选出，只能选（    ）。

    Jackie Chan was born on April 7, 1954, in Hong Kong, China. His parents left mainland China for Hong Kong a short time before he was born. His parents named him “Chan Kong-sang”, which means “born in Hong Kong”. They wanted to celebrate a safe trip to Hong Kong.
    At first, Jackie's family lived in the French Embassy(大使馆).His father was a cook, and his mother was a housekeeper. When Jackie was seven years old, his family moved to Australia. His father got a job in the American Embassy. Later, back in Hong Kong, Jackie's father sent him to the China Drama Academy. Jackie studied and worked 19 hours a day. The students practiced Kong Fu and learned how to do many stunts(特技表演)there.
     When Jackie was 17, he began to do dangerous stunts for films. In the early 1980s, Jackie went to Hollywood, but he wasn't very successful. He went on to make films in Hong Kong and had great success. Finally, in 1995,Jackie Chan became famous in the United States. Today, Jackie Chan has both Chinese and American fans and his films make millions of dollars.

过一点可以画____条射线，可以画____条直线．过两点可以画____直线．

小柯看到香烟盒上印有“吸烟有害健康”，于是他利用实验探究“烟草浸出液对种子萌发和幼苗生长的影响。”

实验材料：黄豆、烟草及其他材料

探究步骤：

Ⅰ．用烟草、蒸馏水制得烟草浸出液（原浸液），浓度视为100％，再通过稀释原浸液得到浓度为70％、40％的浸出液。

Ⅱ．取4个同规格的培养皿，编号为1，2，3，4，并在里面铺上等量的干棉花。

Ⅲ．在每个培养皿中放20粒同样饱满的黄豆，盖上盖子。

Ⅳ．每天定时向各培养皿中喷洒等量、对应浓度的浸出液，并记录数据。其中第5天的数据如下表：

判断题：根瘤菌具有固氮作用。（  ）