（Ⅰ）若 $\overrightarrow{m}$ ⊥ $\overrightarrow{n}$ 且0＜x＜π，试求x的值；

（Ⅱ）设f（x）= $\overrightarrow{m}$ • $\overrightarrow{n}$ ，试求f（x）的对称轴方程和对称中心．

此时北京时间是（  ）

    American and British people use different greetings. In the USA the commonest greeting is “Hi”. In Britain it is "Hello!" or "How are you?"“Hi!" is creeping（不知不觉地进入）into British, too. When they are introduced to someone, the Americans say, "Glad to know you. ” The British say, "How do you do?" or "Pleased to meet you. "When Americans say "Good-bye", they nearly always add, "Have a good day. " or “Have a good trip. " etc. to friends and strangers alike. Britons are already beginning to use “Have a good day. ”
    The British usually use "got" in the sense of “have”. The Americans hardly ever do. AmE: Do you have a car, room, etc. ? Yes, I do. BrE: Have you got a car, room, etc. ? Yes, I have.
    There are a number of differences between American and British English in the spelling of words, e. g. check（US）/cheque（UK）. Many American words ending in “or”, e. g. honor, labor are spelt in British English with an “our,” e. g. honour, labour. Many verbs in American English with “ize” or “izing” forms, e. g. organize, realizing are spelt in BrE with “ise” or “ising”, e. g. organise, realising. In American English, “practice” is used both for the verb and noun. In BrE, the verb is spelt “practise”, and the noun “practice. ” In AmE, one writes “traveler,” while in BrE, one writes “traveller”.
    It was once predicted that British and American English would become separate (各自的)languages finally. But the opposite has happened. The links（联系）between the two countries are so strong that linguistically（语言上）,and probably culturally（文化上）too, they are closer together than ever before.
    AmE—— American English   BrE——British English

B

    “Can I take your order?”Night after night．I had to say this as l worked in my family's restaurant．My father was a fantastic cook．He wanted me to cook with him．but I didn't like cooking．Because of the restaurant, my father was always busy．He never had time to play soccer with me．

    During my high school and college years，I worked with my family at night．But I always avoided the kitchen．I couldn't wait to graduate (毕业),so I could move away from the family business(生意)．Several days before my graduation day, my father and I started looking at new cars．Finally, we found the right car．I was sure that my father would give it to me as my graduation gift．

    On my graduation day, my father gave me a book as a gift．It was his old cookbook．I was so angry that I gave it back to him and ran out of the house．I soon moved away and started my own business．Although I often saw my father during holidays，we never talked about the graduation gift．Then one day, I got a call that my father was sick．I went to see him because l was very worried．

    That night, I looked through my father's books and saw the cookbook that he had given me years before．I carefully opened the cookbook and went through it．Then I found something that made me cry．It was a check(支票)for$30，000 dated(注有日期)the day of my graduation．And the price of the car my father and I chose all those years ago was $30,000．