采用海砂配置混凝土时，对预应力钢筋混凝土，海砂中的氯离子含量不应大于0.06%。

对流活动强弱及厚度主要取决于近地面气温高低和气温垂直递减率。若只考虑气温因素，下列说法正确的是

A．对流层厚度，白天小于夜晚

B．气温垂直递减率，城市大于郊区

C．对流层厚度，海南小于辽宁

D．对流层厚度的季节变化，新加坡大于新疆的乌鲁木齐

     阅读下面短文,按照句子结构的语法性和上下文连贯的要求,在空格处填人一个适当的

词或使用括号中词语的正确形式填空。

     This happened in a third-grade classroom. Jim sat  1  his desk and all of a sudden, there was a

puddle(一滩水) between his feet and the front of his trousers was wet. He felt his heart was going to

stop. He knew   2   would happen when his classmates found out. He looked up and there came the

teacher with   3   look in her eyes that said he   4 (discover).

     As the teacher was walking towards   5  , a classmate named Susie was carrying a goldfish bowl full

of water to her desk. Suddenly, Susie tripped (绊倒) and,   6  (strange), dumped the whole bowl of

water in Jim's lap. He pretended to be angry, but all the while he was saying deep in his heart, "Thank

you!"

     Jim became the object of sympathy instead of ridicule (嘲笑). The teacher brought him gym shorts to

put on. All the others crawled(爬) on their hands and knees,   7  (clean) up around his desk. But  8  

life would have it, the ridicule that should have been his had been transferred (转移) to Susie. She tried

to help,   9  they told her to leave the room   10  school was over, Jim walked over to Susie and

whispered, "You did that on purpose, didn't you?"

     Susie whispered back, "I wet my trousers once, too!"

电力电缆不需停电的工作应填用电力电缆第二种工作票。

扑救火灾的基本方法是什么？

对人体来说细菌的菌体(O)抗原属于( )

A．自身抗原
B．异种抗原
C．同种异型抗原
D．异嗜性抗原
E．半抗原