1.“I am sorry I broke your mirror .”“ Oh, really ?________. ” A. It’s ok with me. B. It doesn’t matter .C. Don’t be sorry. D. I don’t care.选B,It doesn't matter是对I'm sorry的固定回答。因此此为最佳答案。2.________ it is to jump into a river on a hot summer day ! A. what fun B. how fun C. what a fun D. what funny 选A,fun在这里作为名词表示“乐趣”,因此只能用What作引导词。fun作名词时不可数,不能选C。3. After______ , he realized that he was wrong in doing that .A. sometimes B. some time C. sometime D. some times 选B,sometimes表“有时”,是表示程度的副词;some times表示“多少倍”即倍数,sometime表示某个不确切或不具体的时间,表示“某个时候”,而不是一段时间,所以A、C、D都错。4. I, _______ your good friend , will try my best to help you out .A. who ,is B. which ,is C. that ,is D. who , am 选A,正确。5. Who can think of a situation ________this word can be used ?A. which B. that C. where D. in that 选C,正确。6. The doctor advised Tom strongly that he should take a holiday ,but _______ didn’t help.A. it B. who C. which D. he 选A,正确。7.Can you believe that in ______ a rich country there should be ______ many poor people ?A. such ,such B. such ,so C. so ,so D. so ,such 选B,so和such意思差不多,但such后面接名词或名词短语,so是副词,修饰形容词和副词。8.The way you thought of _________ the work is very good .A. doing B. to do C. that do D. which to do 选A,正确。9.I’ll remember the time_______ we spent together in the country .A. when B. at which C. that D. during which 选A,正确。10.Rencently I bought an ancient vase,_______ was very reasonable.A. which price B. the price of which C. its price D. the price of that 选B,若选C或D则应另起一句话。A中的"which"没有表示出“它的”的意思,应改为"whose"。B选项则表示出了"它的价格"的意思。11.It’s a long trip and we’ll have to _______ early tomorrow morning .A. start off B. go off C. take off D. put off 选A,正确。12.John _______ the office as he was passing ,but Mary was out .A. called for B. called up C. called on D. called at 选B,call for:提倡;call up:打电话给;call on:号召,呼吁;call at:访问13.You can ______us in the discussion if you ______.A. join ,wish to B. join in ,want to C. attend , don’t want to D. take part in , hope so 选B,正确。14._______ the internet is bridging the distance between people ,it may also be breaking some homes or will cause other family problems.A. when B. while C. as D. if 选C,as在这里表示“当...之时”,"may"的使用说明两句话并不是并列关系,用when,while不合适。if用在这里意思根本说不通。15.Many people believe we are heading for environmental disaster(灾难) _______we radically(根本地) change the way we live .A. but B. though C. unless D. in case 选C,unless表示“除非”,用在这里表转折关系,能使语句通顺。though表示“虽然”;in case表示“万一”,用在这里都不通顺。你选对的应该都明白,我都没做解释。其他的解释希望能有点帮助。