题目

My now 7 year old grandson, who lives 100 miles away, has had my mobile phone number memorized since he was 4．Since then, he has   36   me every night before he   37   to tell me about his day or just to say Good Night Grandma． He also     38   calls me at other times during the day just to   39    a happy or sad moment．Many times he's dribbling （运球）a basketball with one hand,    40   laughing with a friend about something that I never quite   41   about, or crying about something he may or may not want to talk about while I’m on the other e（1）下面核反应中X代表中子的是______A． 147N+ 42He→ 178O+XB． 42He+ 2713Al→ 3015P+XC． 23490Tn→ 23491Pa+XD． 23592U+ 10n→ 14456Ba+ 8936Kr+3X（2）在光滑的水平面上有甲、乙两个物体发生正碰，已知甲的质量为1kg，乙的质量为3kg，碰前碰后的位移时间图象如图所示，碰后乙的图象没画，则碰后乙的速度大小为______m/s，碰撞前后乙的速度方向______（填“变““不变“）（3）从某金属表面逸出光电子的最大初动能Ek与入射光的频率v的图象如下图所示，则这种金属的截止频率是______HZ；普朗克常量是______J/Hz．