题目

甲、乙两个物体从同一地点沿同一方向做直线运动，其v – t图象如图所示。关于两车的运动情况，下列说法正确的是 A．在t = 1s时，甲、乙相遇 B．在t = 2s时，甲、乙的运动方向均改变 C．在t = 4s时，乙的加速度方向改变 D．在t = 2s～t = 6s内，甲相对乙做匀速直线运动 6．  答案：【答案】D 【解析】 A、甲、乙两个物体从同一地点沿同一方向做直线运动，当位移相等时，两者相遇．根据速度图象与坐标轴围成面积表示位移，可知，在t=1s时，乙的位移大于甲的位移，说明两者没有相遇，故A错误； B、由图知，在t=2s时甲乙的速度方向没有改变，故B错误； C、速度图象的斜率表示加Walking down a path through some woods in Georgia, I saw a water puddle (水坑) ahead on the path. I walk around to the side of the path that wasn’t covered by water and ______. As I reached the puddle, I was suddenly attacked! Yet I did nothing for it was so ______. I stepped back and my attacker stopped attacking me. ____attacking more, he flied in the air with its graceful ______ in front of me. Had I been hurt, I wouldn’t have found it amusing but I was unhurt, it was ______ and I was laughing. After all, I was being attacked by a butterfly!I took a step forward, and my attacker rushed me again. He pushed and _____me in the chest with his head and body over and over again with all his might. It’s just not everyday that ______ is attacked by a butterfly, so I stopped to find out the ______. My attacker moved back as well to ______ on the ground. That’s when I discovered  why my ______ was charging me only moments earlier. He had a mate beside the puddle ______ he landed and she was dying.Sitting close beside her, he opened and closed his wings as if to fan her. I could only ______ the love and courage of that butterfly in his concern for his mate, even though she was ______ dying and I was so large. He did so just to give her those extra few ______ moments of life. Now I knew why and what he was ______. I couldn’t do anything other than reward him by changing my ______ to the more difficult side of the puddle. He had truly ______ those moments to be with her, undisturbed. I cleaned the mud from my boots and left.Since then, I’ve always tried to remember the ______ of that butterfly whenever I see huge ______ facing me. I use that butterfly’s courage as an inspiration to ____myself that good things are worth striving for.1.A. mud B. grass C. stone D. earth2.A. unnecessary B. unpredictable C. unbelievable D. understandable3.A. Or rather B. Or so C. Instead of D. Other than4.A. feet B. hands C. feather D. wings5.A. funny B. surprising C. shocking D. exciting6.A. grasped B. hit C. took D. seized7.A. it B. ones C. one D. that8.A. reason B. purpose C. origin D. direction9.A. run B. fly C. stand D. land10.A. fighter B. attacker C. competitor D. pet11.A. what B. which C. where D. why12.A. understand B. give C. remember D. admire13.A. doubtfully B. clearly C. eventually D. actually14.A. previous B. precise C. precious D. preferable15.A. fighting for B. looking for C. struggling with D. providing for16.A. goal B. way C. opinion D. attitude17.A. enjoyed B. left C. earned D. remembered18.A. competition B. intelligence C. determination D. courage19.A. barriers B. equals C. rivers D. deaths20.A. request B. permit C. remind D. forbid