男,70岁。突发剧烈头痛、呕吐、左侧肢体活动障碍6小时,昏迷小时。1小时前呕暗红色血液1次。应首先考虑的呕血原因是
A、急性胃黏膜病变A
暂无解析
北京和呼和浩特相距660千米.一列火车从呼和浩特开出,每时行驶48千米;另一列火车从北京开出,每时行驶72千米.两列火车同时开出,相向而行,经过几时相遇?两车相遇时,从北京开出的火车比从呼和浩特开出的火车多行了多少千米?
如图所示,一竖直绝缘轻弹簧的下端固定在地面上,上端连接一带正电小球P,小球所处的空间存在着竖直向上的匀强电场,小球平衡时,弹簧恰好处于原长状态:现给小球一竖下向上的初速度,在小球从开始运动至达到最高点的过程中,以下说法正确的是
swim_______(现在分词)
阅读理解,根据短文内容判断正(T)误(F)。
It'sSundaymorning.ThestudentsofClass3aregivingtheirclassroomagoodcleaning.
MissHuang,theirteacher,isworkingwiththem.Thechildrenarebusy.Somearecarryingwater;
somearecleaningthewindows;othersaresweepingthefloor.ZhangHuaisputtingupamaponthe
wall.ItisamapofChina.WangFeiandWeiQingaremendingsomebrokenchairs.Thechildrenare.
listeningtotheradiowhiletheyareworking.Theclassroomlooksniceandbrightafterthecleaning.
Thechildrenareveryhappy.Theygohomeforlunchatnoon.
()1.ThechildrenareplayingintheirclassroomonSundaymorning.
()2.MissHuang,theirmother,isworkingwiththem.
()3.ThereisamapofChinaonthewall.
()4.Twoofthemarerepairingthebrokenchairs.
()5.Theyaresingingwhiletheyareworking.
足球比赛时,裁判用抛硬币猜正反面的方法让双方决定谁先要场地,谁先要发球权.这种做法是________的,因为________.