（1950年10月5日）斯大林致***电……如果中国只是消极地等待，而不是进行一场认真的较量，……显示出自己的力量，那么中国就得不到这些让步。……甚至连台湾也得不到，……如果战争不可避免，那么让它现在就打，而不要过几年以后，……您（指***）肯定地说，在由于朝鲜事件而出现新战争的情况下，中国国内将会出现极大的不满情绪，因为国内非常渴望和平。……这个问题只能由中国同志来决定。该致电表明：①斯大林要求中国出兵朝鲜 ②中国决意参加朝鲜战争③中国的战略重点在台湾而不在朝鲜 ④美苏战略争夺的重点在东亚

    While  Tom and Mary were on holiday at the seaside, they enjoyed 1seagulls(海鸥). They learned a lot about these2birds.
They will often come close to you on the beach when you are eating something. If you3a piece of bread to them, they will take it away quickly.
    Seagulls swim well, but they do not often dive(潜水)for fish. They are4good at flying with their wings(翅膀)。When a seagulls is flying, It puts its legs5its body. Tom often watched them6close to the ground because he like the way they7the air with their wings and put8their feet before they touched the ground. Mary liked to see them flying over the9smoothly(熟练的) and quietly without their wings moving, 10she said she didn't like the noise they made. 

在我国基本型乘用车（轿车）市场上，不但汽车降价可以起到促销作用，减少税费、油价下降也对拉动销量有明显影响。假设D和D1中有一条是汽车需求曲线，另一条是某生活必需品需求曲线，在价格及其他因素不变的情况下，下列判断正确的是

人体的免疫器官主要有（    ）

如图，⊙O的半径为2，点O到直线$l$的距离为3，点P是直线$l$上的一个动点，PB切⊙O于点B，则PB的最小值是(     )