已知测得t0=20s；t15=40S，则SDI为（）。

[单选题]在测SDI时读取t15的水样体积为（）。A .300ml；B .400ml；C .500ml；D .600ml

[单选题]调试超声波检测仪时，测得t0=5μs，已知某测点声距L=40cm，仪器显示声时为105μs，则超声波在混凝土中传播的声速为()。A.3636m/sB.

[单选题]调试超声波检测仪时，测得t0=5μs，已知某测点声距L=40cm，仪器显示声时为105μs，则超声波在混凝土中传播的声速为()。A.3636m/sB.

[单选题]已知质点沿半径为40m圆做圆周运动，其运动规律为：S＝20t（S以cm计，t以s计）。若t＝1s，则点的速度与加速度的大小为（）。A . 20cm／s；10cm／s2B . 20c／ms；10cm／s2C . 40cm／s；20cm／s2D . 40cm／s；10cm／s2

[单选题]已知f（t），为求f（t0-at）则下列运算正确的是（其中t0，a为正数）（）A . f（-at）左移t0B . f（-at）右移C . f（at）左移t0D . f（at）右移

[主观题](T15)A．ORIGINB．COMMUNICATE WITHC．WRITTEN DOWND．LEARN A.THE MORE WE READ AND(T13)_______B．WHICH COULD BE(T14)______C．THE(T15)______OF LANGUAGE IS A MYSTERYD．THEY COULD(T16)______EACH OTHER HOW MEN FIRST LEARNT TO INVENT WORDS IS UNKNOWN; IN OTHER WORD

[主观题](T15)A．DROP OUTB．FOR YOUR SOCIETYC．TAKE EFFECTD．THE LAUNCHING PAD A.THE FAMOUS LAW OF DIMINISHING RETURNS BEGINS TO(T13)______B．YOU ARE ON(T14)______C．YOU CAN SUCCESSFULLY(T15)______IN GRADE SCHOOLD．PROVIDE MANPOWER(T16)______ WHEN THEY ADVISE YOUR K

[主观题](T15)A．STOCKS AND SHARESB．GET INTO THE STOCK EXCHANGEC．FROM THE OLD ONED．OF TIME A.NEITHER ALLOWED TO BECOME PARTNERS IN STOCKBROKING FIRMS,NOR TO BE AUTHORIZED DEALERS IN(T13)______B．THE NEW FLOOR IS GOING TO BE DIFFERENT(T14)______C．IT IS ONLY A MA

[主观题](T15)A．SEE THE WORLDB．ALIEN TOC．AT RANDOMD．LIVE IN A.RESIDENTS IN THESE COMMUNITIES WERE PHONED(T13)______AND ASKED THE SAME QUESTIONSB．WHY THE "STANDARD TEMPLATES" OF THE NEWSROOM SEEM(T14)______MANY READERSC．JOURNALISTS ARE MORE LIKELY TO(T15)___

[主观题](T15)A．TEND TOB．CONSIDEREDC．ARISED．THINK OF A.IT MAY BE(T13)______FOOLISHB．MISUNDERSTANDINGS(T14)______BETWEEN PEOPLE FROM CULTURESC．NO ONE WOULD(T15)______KEEPING A BUSINESS FRIENDD．GUESTS(T16)______FEEL THEY ARE NOT HIGHLY REGARDED IN SOCIAL LIFE,