木块与小车向右做匀速直线运动,遇到一障碍物时,小车停下,木块从车上的a点滑至b点(如图甲),其原因是____ ;为测量木块与小车之间摩擦力的大小和方向,小明在障碍物上固定了弹簧测力计拉住木块,用手拉着小车向左运动,结果如图乙所示,则木块受到向____ (选填“左”或“右”)的摩擦力,其大小是____ N.
加拉帕格斯群岛的地雀原来属于同一个物种,从南美大陆迁来后,分布在不同的海岛上,从而形成了____ .这样,不同的种群就可能出现不同的____ ,且互不影响,从而使不同的种群的基因频率发生不同的变化.同时由于各岛屿上的条件不同,所以自然选择对各种群所起的作用也不相同,久而久之,各种群的____ 就会形成明显的差异,并逐步出现____ ,从而使原来属于同一个物种的地雀,就成了不同的物种.由此可见,隔离是物种形成的必要条件.上述一个物种进化成多个不同的物种,体现了生物多样性中的物种多样性.生物多样性还包括基因多样性和____ 多样性.
电视已经走进了千家万户,是我们生活的重要组成部分。每个人都有自己最喜爱的电视节目。下面是五个人的描述,请根据他们的描述从A-F中为他们选择合适的电视节目____ I am 73 years old. I often watch TV in my free time. Of all the programs, I like the news best. Through the TV, I can learn what is happening in our country and in the world. At seven every evening , I always sit in front of the TV.____ I am a grandma. I like Chinese traditional opera. From Monday to Thursday, I usually turn on the TV at half past seven. The programs from CCTV7 are my best.____ I am a basketball fan. I like playing basketball very much. But I am too busy. So I have to watch it on the TV. Every night, I watch the match till midnight.I am crazy about it , especially NBA____ I am a housewife. I do the housework all day, I'd like to watch TV at night. I prefer to see soap operas like ‘palace”, “meteoric garden” and so on.Because they can make me feel relaxed.____ I am the only son in the family. I am in Grade Five. I like cartoons best. I often watch cartoons on the TV after doing the homework. A B C D E F.