20+4=____ 29-9=____ 65-5=____ 40+8=____ 32-2=____ 14-6=____
26-6=____ 50+5=____ 7+9____ 30+3=____ 58-8=____ 7+90=____
20-9=____ 15-9=____ 13-5=____ 11-6=____ 6+10-8=____ 12-3-6=____ 6+8+10=____ 11-3-7=____ 0+12=____ 13-6-3=____ 14-9+8=____ 12-5=____
如图所示的火警报警装置,R1为热敏电阻,若温度升高,则R1的阻值会急剧减小,从而引起电铃电压的增加,当电铃电压达到一定值时,电铃会响.下列说法正确的是( )
如图,在平面直角坐标系xOy中,直线y= 3 x经过点A,作AB⊥x轴于点B,将△ABO绕点B逆时针旋转60°得到△CBD,若点B的坐标为(2,0),则点C的坐标为____.
阅读下面短文,按要求完成各项任务.
Every year animals all around the world take part in some wonderful journeys.Here are the stories of two amazing animal travelers.
Humpback whales ( 座 头 鲸 ) prefer a slow journey.The humpbacks,
which travel over 10,000kilometers on their journey from Alaska to Hawaii,swim at a relaxing speed of about 1.6kilometers an hour.Although they don't swim fast,humpback whales travel farther than any other kinds of whale.
Every August a fantastic sight can be seen in the skies above Ontario and Montreal﹣millions of amazing Monarch butterflies ( 帝 王 蝶) beginning their 4,000﹣kilometer journey from Canada to Central Mexico.In fact,the journey,which takes about 3months,is longer than the average ( 平 均 的 ) life of the butterfly.Finally many of the butterflies reaching their final place are the great grandchildren or even the great great grandchildren of the butterflies who began the journey in Mexico the year before.
单项式-2x2y3的系数与次数之积为____