Different countries and different people have different manners. We must find out their customs, so that they will not think us ill-mannered. Here are some examples of the things that a wel
猫和老鼠有着天然的关系：老鼠会“装死”，猫则会“假眠”；老鼠昼伏夜出，猫眼则可以随光线的明暗而改变瞳孔的大小，夜间仍可看见东西……由
著名学者彭慕兰认为：与其说工业革命创造了新的财富，不如说新的财富的发现，导致并推动了工业革命，因为工业革命的发生来源于两个方向的驱动
近年来，原油价格持续上涨。为降低对石油的依赖程度，我国乙醇汽油的使用在不断增加，目前，我国已经成为世界第三大生物燃料乙醇生产国。此外
读世界大陆自然植被水平地域分布示意图（部分），回答3一4题。 a地所处自然带为 A．亚热带常绿阔叶林带B．温带落叶阔叶林带 C．亚热带常绿硬叶林
Mr. Li___a secretary for five years in the company, and now he is the general manager of it. A. is B. was C. had been D. has been
It’s kind _________ you to help me with my English. You know, It’s impossible _______ me to pass this exam without your help. A. of , for B. of , of C.
（10分）如图15所示，一束具有各种速率的两种质量不同电量为(q=1.6×10-19)正离子，水平地经过小孔S1射入互相垂直的匀强电场（E＝1.0×105V/m）和匀强磁场
B.
C.
D.
