引力

The craft will acquire sufficient velocity to escape the sun's gravitational attraction.

飞船将获得足够快的速度来脱离太阳的引力。

The greater the mass, the stronger the gravity and the greater the escape velocity.

质量越大，它的引力越大，逃逸速度越大。

Less obviously, the smaller the radius, the stronger the gravity and the greater the escape velocity, too.

容易忽略的是，行星的半径越小，它的引力和逃逸速度也变得越大。

Lanthanides belong to the sixth cycle of the periodic table Ⅲ B family, are all solid metal, they are La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, holmium, erbium, thulium, ytterbium, and lutetium were 15 kinds of metals and their periphery are two layers of electronic 5d16s2, while the peripheral third layer f orbital but never zero to 14, so the external electronic structure of 4f0-145d16s2, and therefore these elements in oxidation number are to 3, very close chemical properties, extraction, when it is difficult to separate them they are mostly multi-element mineral mix, more difficult to increase refining, and their atomic number of 57-71, one by one to increase the number of protons the nucleus, and thus extranuclear electron of gravity is also growing, so that atomic radius decreases with increasing atomic number Z, which makes lanthanides contraction, ionic radius is also reduced, which also makes Zr, Hf, Nb and Ta, Mo and W, the atom and ionic radius very close to each other they also determine a similar nature, resulting in difficult separation, also the tribe Ⅷ of the fifth cycle, ruthenium, rhodium, palladium, and the sixth cycle, osmium, iridium, platinum is very similar in nature, thus The six elements, said platinum group elements.

镧系元素属于周期表第六周期中ⅢB族，全部是固体金属，它们是镧、铈、镨、钕、钷、钐、铕、钆、铽、镝、钬、铒、铥、镱和镥共十五种金属元素，它们的外围两层的电子均是5d16s2，而外围第三层的f轨道电子却从零增加到14个，所以外围电子结构为4f0－145d16s2，而使这些元素氧化数均为＋3，化学性质极为接近，提炼时很难分开，它们的矿石又大多是多种元素混在一起的，更增加提纯难度，它们的原子序数为57－71，核内质子数逐个增加，因而对核外电子引力也不断增强，使原子半径随原子序数Z增加而减小，这就使镧系元素收缩、离子半径也缩小，这也使得Zr和Hf，Nb和Ta、Mo和W等原子和离子半径都很接近、也决定了它们彼此性质类似，以致难以分离、也使第Ⅷ族中第五周期的钌、铑、钯和第六周期的锇、铱、铂在性质上极为相似，因而称这六个元素为铂系元素。

The periodic rise and fall of the sea level under the gravitational pull of the moon.

由于月亮的重力引力所引起的海平面的周期性的涨落。

He would float freely in the chamber, and anything he pulled from his pocket and dropped would float freely next to him.just as if he were in a closed chamber sitting still in a gravity-free region of deep outer space.

他将会在电梯中自由地漂浮着，而无论他从口袋中拿出什么，并且仍掉，这样的东西都会在他身旁自由漂浮。这就好像他是静坐在深层外太空处的一个没有引力的地区。

This lack of uniformity of the force of gravity results from a number of factors.

引力这种非均匀性是由许多因素引起的。

The force of gravity on an object is commonly referred to as its 'weight'.

一个物体的重力通常被称为'重量'。行星的运动也是引力的结果。

A free and rapid descent by the force of gravity .

由于地球引力的作用而引起的自由、快速的下降。

The force of gravity is with us all the time, though we may not feel it.

地球引力无时无刻不存在，尽管我们可能感觉不到它。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了