【单选题】点M沿图示曲线AOB运动,曲线由AO、OB两圆弧组成,AO段圆弧的半径R1 = 18m,OB段圆弧的半径R2 = 24m,取两圆弧交接处O为弧坐标的原点,其正负方向规定如图。已知点的运动方程为 【图片】 ,式中s以米计,t以秒计。则点从运动开始算起的5秒内走过的路程为()。(提示,要先求出速度,算出质点开始反向运动的时刻。分段计算路程)【图片】
【单选题】What might happen to the drivers who illegal substances?
A.
They will be sent to a laboratory.
B.
They will lose their licences.
C.
They will be fined and could lose their licences.
D.
They will be sentenced guilty.
【简答题】我们生活在“水球”上,地球表面的70.8%被水覆盖。 (1)海水晒盐是借助日光和风力使海水中的__________(写化学式)蒸发,得到含有较多杂质的______(写化学式)晶体。 (2)降雨是自然界中水循环的一个环节。_______气体或这些气体在空气中反应后的生成物溶于雨水,会形成酸雨。A、B、C三个地区雨水的pH如下图所示,其中________地区的雨水是酸雨。 (3)请按要求写出初中化学教...
【简答题】已知质点沿x 轴作直线运动,其运动方程为【图片】,式中x 的单位为m,t 的单位为 s.求:t=4 s时质点的速度大小为(填数字) m/s
【判断题】可以通过精馏的方法由35%的乙醇得到无水乙醇。
【简答题】我会按字母表顺序填写: A B( )( )E( )G
【单选题】What might happen to the two codes in the future?
A.
Nothing will happen to them.
B.
There might be another code break off from the two.
C.
They might reunite together.
D.
They might change the rules and scoring system from women's teams.
【单选题】What did the doctor think might happen to Ellen?
A.
She might put on more weight.
B.
She might stop eating too much.
C.
She might have a heart attack.
D.
She might go to another doctor.
【单选题】週に1回 (びょういん)に かよっています。