复发性口腔溃疡的确切病因是（） A.细菌感染 B.病毒感染 C.遗传因素 D.营养障

阅读下面短文，并借助上下文和插图补充所缺信息。每个空格只能填写一个形式正确、与短文意思

相符的英语单词。

     Bob and David are good friends, but they like to joke on each other sometimes. One day they went to

London for their holidays. They went to the (1)______ and bought their tickets. When the train arrived,

Bob got on the train first, but he dropped his (2)______ on the platform (站台) without knowing it. David

was behind him and quickly (3)______ it up. Without saying a word to his friend,he put it in his (4)______.

After they had been in the (5)______ for a little while, they saw the conductor (列车员) coming along,

shouting, "Ticket, please!" Bob (6)______ for his and of course he couldn't find it.

     "Oh, dear, I can't (7)______ my ticket, David." he said.

     "Have another look, Bob; it must be (8)______," said David. "No, I can't find it anywhere. What shall I

do?" "Perhaps you'd better hide under the (9)______ so that the conductor won't see you."

     So Bob crawled (爬) under the seat and lay there quietly. Soon the conductor stood in front of David.

"Ticket, please." he said. David handed him (10)______ tickets and said, "This is mine. The other is my

friend's. He prefers to travel under the seat.''

运输企业的关键客户一般为（）。

A.临时客户

B.一次性托运大宗货物的客户

C.潜力客户

D.致力于发展长期稳定伙伴关系的客户

作为工作态度指标，工作满意度体现了（）的关系。

A.个体与组织

B.个体与工作

C.工作与组织

D.个体与生活

双氧水上升的原因有那些（）.

A、生产中，双氧水温度较高至使一部分水分蒸发

B、双氧水中含有杂质

C、和金属“镍”含量有关

D、双氧水加的太多

（）褶曲的岩层向下拱起，核部由较新的岩层组成。