Earth前面一定加the吗？

Earth前面一定加the吗？

　当earth是表示地球的话，作为世界上独一无二的物体，在前面要加定冠词the的；onearth,downtoearth是词组，有它自己的意思，第一个是究竟，第二个是在地球上。

扩展资料

　It was once thought that the sun travelled around the earth.

人们曾经认为太阳绕着地球转。

The earth takes a year to orbit the sun.

地球绕太阳一周要一年的时间。

What on earth is the effect of the multimedia teaching?

多媒体教学的效果究竟如何？

Arrows would continue to fly forward forever in a straight line were it not for gravity, which brings them down to earth.

要不是重力使箭落向地面，它们将永远以直线往前飞行。