如图表示的是豆科植物和其内部的根瘤菌，根瘤菌为豆类植物提供氮肥，豆类植物为根瘤菌提供有机物，根瘤菌细胞结构和豆科植物细胞结构相比较，主要区别是没有（ ）

School uniforms are common in primary and secondary schools in many countries. Here’s a list of countries below.

	In Brazil, students wear uniforms in private schools. But in public schools, students don’t have to wear uniforms although they might have one. In general, the uniforms are a pair of blue pants and a white T-shirt with the school symbol printed on it.
	School uniforms are used in Cuba. All students wear school uniforms with the color as a symbol of grade level. Children also wear scarves because they are young pioneers(少先队员).
	Japan introduced school uniforms in the late 19th century. Today, school uniforms are very common. Many boys wear white shirts, short pants and caps. Girls’ uniforms might include a gray pleated (褶)skirt and a white blouse.
	In Singapore, all students must wear uniforms. Though the colors are different from school to school. The normal uniform for boys is shorts or long pants, with a shirt (often white), while girls wear white pinafores(连衣裙) or skirts.

右图是法国科学家巴斯德的实验：

他使用了两种瓶来作实验，宽口瓶和鹅颈瓶。两瓶中放入相同的肉汤，并敞口放入同样的环境中（空气、温度、湿度、光照完全相同），而且瓶内和外界空气都是相通的，放置一周后，宽口瓶中的肉汤腐败了，而鹅颈瓶中的肉汤没有腐败。
（1）在这个实验中，为了探究细菌产生的原因，他设置两瓶其他条件都相同，只有一个条件不同，这样的实验叫____ 实验。
（2）本实验的变量是____  。
（3）本实验的对照组是____ ，实验组是____。（填宽口瓶或鹅颈瓶）
（4）本实验说明了细菌的产生是____ 。
A．自然发生的    B．由原已存在的细菌产生的

设集合$A=\left\{x|x\ge 1\right\},B=\left\{x|y={\log }_2\left(x+2\right)\right\}$，则$C_{B}A=\left(\right)$