It began in April of nineteen ninety-four after a plane carrying the presidents of Rwanda and Burundi, both Hutus,was shot down.
VOA: special.2009.03.09
Another way to represent a point in a plane is I've got a radius and I've got an angle from the x-axis, right, and that's a standard thing you might do.
平面上面的点的方法,也就是极坐标,上面那种方法其实是,如果你们喜欢我这么说的话,笛卡尔坐标表示法。
Um-hmm. So, it's going to be the y z nodal plane, or in other words, we can say it's any place where phi is equal to 90 degrees.
嗯,是yz平面,换句话说,是在phi等于90度的面。
The first plane ever to fly faster than the speed of sound was the X-1 in nineteen forty-seven.
VOA: special.2010.07.07
Then, I gave you one other very important example of a particle moving in the x-y plane.
下面我再拿一个重要的例子,质点在 x-y 平面内的运动
The pilot spent fifty hours in a simulator -- a copy of the plane on the ground -- preparing for his ten-minute flight.
VOA: special.2010.07.07
Our picture now is going to be some particle that's traveling in the x-y plane.
我们现在的情景是在 x-y 平面内,运动的质点
In nineteen-ninety seven, John Denver was killed when the plane he was piloting crashed.
VOA: special.2009.07.10
And that's the following. Let's take a particle that is moving in the x-y plane, so that at one instance-- sorry, let me change this graph-- is here--oh, this is bad.
接下来,我们来看一个物体,在 x-y 平面内运动,在这个例子中,对不起,我要重画一下这个图,在这里,这画得不好
In April,1994 unknown assassins shot down the plane carrying then-President Juvenal Habyarimana.
VOA: standard.2009.04.10
Abdel Basset al-Megrahi received a warm welcome from flag waving Libyan supporters as he stepped off the plane Thursday in Tripoli, after his release from custody in Scotland on compassionate grounds.
VOA: standard.2009.08.21
As state television cameras chronicled his exploits for the Tuesday evening news, he co-piloted an amphibious firefighting plane, taking on water from a river and dumping it on burning fires in the Ryazan Region.
VOA: standard.2010.08.10
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